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National Center for Health Statistics (US). Health, United States, 2012: With Special Feature on Emergency Care. Hyattsville (MD): National Center for Health Statistics (US); 2013 May.

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Health, United States, 2012: With Special Feature on Emergency Care.

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Appendix IIDefinitions and Methods

This appendix contains an alphabetical listing of terms used in Health, United States, and these definitions are specific to the data presented in this report. The methods used for calculating age-adjusted rates, average annual rates of change, relative standard errors, birth rates, death rates, and years of potential life lost are described. Included are standard populations used for age adjustment (Tables I and II); the years when the revisions for International Classification of Diseases (ICD) codes were in effect (Table III); codes for cause of death from the 6th through 10th revisions of ICD (Table IV); and comparability ratios between the 9th and 10th revisions (ICD–9 and ICD–10) for selected causes (Table V); imputed family income percentages from the National Health Interview Survey (NHIS) (Table VI); an analysis of the effect of added probe questions for Medicare and Medicaid coverage on health insurance rates in NHIS (Table VII); industry codes from the North American Industry Classification System (NAICS) (Table VIII); and ICD–9 Clinical Modification (ICD–9–CM) codes for external causes of injury, diagnostic, and procedure categories (Tables IXXII). Standards for presenting federal data on race and ethnicity are described, and sample tabulations of NHIS data comparing the 1977 and 1997 Office of Management and Budget standards for the classification of federal data on race and ethnicity are presented in Tables XIII and XIV.

Table I. United States projected year 2000 standard population and age groups used to age-adjust data

Table II. United States projected year 2000 standard population and proportion distribution, by age, for age-adjusting death rates prior to 2001

Table III. Revision of the International Classification of Diseases (ICD), by year of conference by which adopted and years in use in the United States

Table IV. Cause-of-death codes, by applicable revision of the International Classification of Diseases (ICD)

Table V. Comparability of selected causes of death between the 9th and 10th revisions of the International Classification of Diseases (ICD)

Table VI. Imputed family income percentages in the National Health Interview Survey, by selected characteristics: United States, 1990–2011

Table VII. Percentage of persons under age 65 with Medicaid or who are uninsured, by selected demographic characteristics, using Method 1 and Method 2 estimation procedures: United States, 2004

Table VIII. Codes for industries, based on the North American Industry Classification System (NAICS)

Table IX. Codes for external causes of injury, from the International Classification of Diseases, 9th Revision, Clinical Modification

Table X. Codes for diagnostic categories, from the International Classification of Diseases, 9th Revision, Clinical Modification

Table XI. Codes for procedure categories for National Hospital Discharge Survey data, from the International Classification of Diseases, 9th Revision, Clinical Modification

Table XII. Codes for procedure categories for Healthcare Cost and Utilization Project data, from the International Classification of Diseases, 9th Revision, Clinical Modification

Table XIII. Current cigarette smoking among adults aged 18 and over, by race and Hispanic origin under the 1997 and 1977 Standards for federal data on race and ethnicity: United States, average annual 1993–1995

Table XIV. Private health care coverage among persons under age 65, by race and Hispanic origin under the 1997 and 1977 Standards for federal data on race and ethnicity: United States, average annual 1993–1995

A · B · C · D · E · F · G · H · I · L · M · N · O · P · R · S · T · U · V · W · Y

A

Acquired immunodeficiency syndrome (AIDS)

Human immunodeficiency virus (HIV) is the pathogen that causes AIDS, and HIV disease is the term that encompasses all the condition’s stages—from infection to the deterioration of the immune system and the onset of opportunistic diseases. However, AIDS is still the term most people use to refer to the immune deficiency caused by HIV. An AIDS diagnosis (indicating that the person has reached the late stages of the disease) is given to people with HIV who have CD4+ cell (also known as T cells or T4 cells, which are the main target of HIV) counts below 200 cells per cubic millimeter (fewer than 200 cells/μL) or less than 14% of total lymphocytes, or who have been diagnosed with at least one of a set of opportunistic diseases. All 50 states and the District of Columbia report AIDS cases to CDC using a uniform surveillance case definition and case report form. The case reporting definitions were expanded in 1985 (see MMWR 1985;34:373–5); 1987 [MMWR 1987;36(SS–01):1S–15S]; and 1993 for adults and adolescents [MMWR 1992;41(RR–17):1–19]; and in 1994 for pediatric cases [MMWR 1994;43(RR–12):1–19]. The revisions incorporated a broader range of AIDS-indicator diseases and conditions and used HIV diagnostic tests to improve the sensitivity and specificity of the definition. The 1993 expansion of the case definition caused a temporary distortion of AIDS incidence trends.

In 2005, CDC collaborated with the Council of State and Territorial Epidemiologists (CSTE) to recommend a change in the AIDS case definition to require laboratory confirmation of HIV infection in addition to a CD4+ T-lymphocyte count of fewer than 200 cells/μL, a CD4+ T-lymphocyte percentage of total lymphocytes of less than 14%, or diagnosis of an AIDS-defining condition. This CDC/CSTE recommendation has been incorporated into the 2008 HIV infection case definition, which includes AIDS (stage 3) [see MMWR 2008;57(RR–10):1–8]. In 1996, regimens of proven combinations of medications, known as highly active antiretroviral therapy (HAART), became the standard of care for HIV and AIDS. These therapies have prevented or delayed the onset of AIDS and premature death among many HIV-infected persons, and this should be considered when interpreting trend data. AIDS surveillance data are published annually by CDC in the HIV/AIDS Surveillance Report, available from: http://www.cdc.gov/hiv/topics/surveillance/resources/reports/index.htm. [Also see Appendix II, Human immunodeficiency virus (HIV) disease.]

Active physician

See Appendix II, Physician.

Activities of daily living (ADL)

ADLs are activities related to personal care and include bathing or showering, dressing, getting into or out of bed or a chair, using the toilet, and eating. In the National Health Interview Survey, respondents were asked whether they or family members aged 3 and over need the help of another person with personal care because of a physical, mental, or emotional problem.

In the Medicare Current Beneficiary Survey, if a sample person had any difficulty performing an activity by him- or herself and without special equipment, or did not perform the activity at all because of health problems, the person was categorized as having a limitation in that activity. The limitation may have been temporary or chronic at the time of interview. Sampled people who were administered a community interview answered questions about health status and functioning themselves, if able to do so. For persons in a long-term care facility, a proxy such as a nurse answered questions about the sample person’s health status and functioning. Starting in 1997, interview questions for people residing in long-term care facilities were changed slightly from those administered to people living in the community, in order to differentiate residents who were independent from those who received supervision or assistance with transferring, locomotion on unit, dressing, eating, toilet use, and bathing. [Also see Appendix II, Complex activity limitation; Instrumental activities of daily living (IADL); Limitation of activity.]

Admission

The American Hospital Association defines admissions as persons, excluding newborns, accepted for inpatient services during the survey reporting period. (Also see Appendix II, Days of care; Discharge; Inpatient.)

Age

Age is reported as age at last birthday (i.e., age in completed years), often calculated by subtracting the date of birth from the reference date, with the reference date being the date of the examination, interview, or other contact with an individual.

Mother’s (maternal) age is reported on the birth certificate by all states. Birth statistics are presented for mothers aged 10–49 through 1996 and aged 10–54 starting in 1997, based on mother’s date of birth or age as reported on the birth certificate. The age of the mother is edited for upper and lower limits. When the age of the mother is computed to be under 10 or 55 and over (50 and over in 1964–1996), it is considered not stated and is imputed according to the age of the mother from the previous birth record of the same race and total birth order (total of fetal deaths and live births). Before 1963, not-stated ages were distributed in proportion to the known ages for each racial group. Beginning in 1997, the birth rate for the maternal age group 45–49 has included data for mothers aged 50–54 in the numerator and has been based on the population of women aged 45–49 in the denominator. Beginning with 2003 data, age of mother is imputed for stated ages 8 and under and 65 and over, for births occurring in states using the 2003 revision of the birth certificate. Starting with 2007 data, age of mother is imputed for all births for stated ages 8 and under and 65 and over. As with data for earlier years, age is imputed according to the age of mother from the previous record with the same race and total birth order.

Age adjustment

Age adjustment is used to compare risks for two or more populations at one point in time or for one population at two or more points in time. Age-adjusted rates are computed by the direct method by applying age-specific rates in a population of interest to a standardized age distribution, to eliminate differences in observed rates that result from age differences in population composition. Age-adjusted rates should be viewed as relative indexes rather than actual measures of risk.

Age-adjusted rates are calculated by the direct method, as follows:

i=1nri×(pi/P)

where ri = rate in age group i in the population of interest

pi = standard population in age group i

P=i=1npi

n = total number of age groups over the age range of the age-adjusted rate.

Age adjustment by the direct method requires the use of a standard age distribution. The standard for age-adjusting death rates and estimates from surveys in Health, United States is the projected year 2000 U.S. resident population. Starting with Health, United States, 2000, the projected year 2000 U.S. standard population replaced the 1970 civilian noninstitutionalized population for age-adjusting estimates from most NCHS surveys; and starting with Health, United States, 2001, it was used uniformly and replaced the 1940 U.S. population for age-adjusting mortality statistics and the 1980 U.S. resident population, which previously had been used for age-adjusting estimates from the National Health and Nutrition Examination Survey.

Changing the standard population has implications for racial and ethnic differentials in mortality. For example, the mortality ratio for the black to white populations is reduced from 1.6 using the 1940 standard to 1.4 using the 2000 standard, reflecting the greater weight the 2000 standard gives to the older population, in which race differentials in mortality are smaller.

Age-adjusted estimates from any data source presented in Health, United States may differ from age-adjusted estimates based on the same data presented in other reports if different age groups are used in the adjustment procedure.

For more information on implementing the 2000 population standard for age-adjusting death rates, see: Anderson RN, Rosenberg HM. Age standardization of death rates: Implementation of the year 2000 standard. National vital statistics reports; vol 47 no 3. Hyattsville, MD: NCHS; 1998. Available from: http://www.cdc.gov/nchs/data/nvsr/nvsr47/nvs47_03.pdf. For more information on the derivation of age-adjustment weights for use with NCHS survey data, see: Klein RJ, Schoenborn CA. Age adjustment using the 2000 projected U.S. population. Healthy People 2010 statistical notes, no 20. Hyattsville, MD: NCHS; 2001. Available from: http://www.cdc.gov/nchs/data/statnt/statnt20.pdf. The projected year 2000 U.S. standard population is available from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program: http://seer.cancer.gov/stdpopulations/stdpop.singleages.html.

  • Mortality data—Death rates are age-adjusted to the projected year 2000 U.S. standard population (Table I). Prior to 2001 data, age-adjusted rates were calculated using standard million proportions based on rounded population numbers (Table II). Starting with 2001 data, unrounded population numbers are used to age-adjust. Adjustment is based on 11 age groups, with two exceptions. First, age-adjusted death rates for black males and black females in 1950 are based on nine age groups, with under 1 and 1–4 combined as one group, and 75–84 and 85 and over combined as one group. Second, age-adjusted death rates by educational attainment for the age group 25–64 are based on four 10-year age groups: 25–34, 35–44, 45–54, and 55–64.
    Age-adjusted rates for years of potential life lost before age 75 also use the projected year 2000 standard population and are based on eight age groups: under 1, 1–14, 15–24, and 10-year age groups through 65–74.
  • National Health and Nutrition Examination Survey (NHANES)—Estimates based on the National Health Examination Survey and NHANES are generally age-adjusted to the projected year 2000 U.S. standard population by using five age groups: 20–34, 35–44, 45–54, 55–64, and 65–74 or 65 and over (Table I). Prior to Health, United States, 2001, these estimates were age-adjusted to the 1980 U.S. resident population.
  • National Health Care Surveys—Estimates based on the National Hospital Discharge Survey, the National Ambulatory Medical Care Survey, and the National Hospital Ambulatory Medical Care Survey are age-adjusted to the projected year 2000 U.S. standard population (Table I). Information on the age groups used in the age-adjustment procedure is contained in the footnotes to the specific tables.
  • National Health Interview Survey (NHIS)—Estimates based on NHIS are age-adjusted to the projected year 2000 U.S. standard population (Table I). Prior to Health, United States, 2000, NHIS estimates were age-adjusted to the 1970 civilian noninstitutionalized population. Information on the age groups used in the age-adjustment procedure is contained in the footnotes to the specific tables.

Alcohol consumption

Alcohol consumption is measured differently in the following data systems. (Also see Appendix II, Binge drinking.)

  • Monitoring the Future (MTF) Study—This school-based survey of secondary school students collects information on alcohol use by using self-completed questionnaires. To determine whether they have tried alcohol in their lifetime, students are asked a preliminary alcohol consumption (defined as beer, wine, liquor, and any other beverage that contains alcohol) screening question: “Have you ever had any alcoholic beverage to drink—more than just a few sips?” Students who reply in the affirmative are then asked additional questions about their alcohol consumption over different time frames: “On how many occasions (if any) have you had alcohol to drink—more than just a few sips... in your lifetime, ...in the last 12 months, ...in the last 30 days?” A subsequent question asks, “Think back over the last two weeks. How many times have you had five or more drinks in a row?” A drink is defined as a bottle of beer, a glass of wine, a shot glass of liquor, a mixed drink, etc.
  • National Health Interview Survey (NHIS)—Starting with the 1997 NHIS, information on alcohol consumption has been collected in the Sample Adult questionnaire. Adult respondents are asked two screening questions about their lifetime alcohol consumption: “In any 1 year, have you had at least 12 drinks of any type of alcoholic beverage?” and “In your entire life, have you had at least 12 drinks of any type of alcoholic beverage?” Persons who report at least 12 drinks in a lifetime are then asked several questions about alcohol consumption in the past year: “In the past year, how often did you drink any type of alcoholic beverage?” and “In the past year, on those days that you drank alcoholic beverages, on the average, how many drinks did you have?” Adults who had at least one drink in the past year were also asked, “In the past year, on how many days did you have five or more drinks of any alcoholic beverage?”
    Levels of alcohol consumption are defined as follows: light drinkers, 3 drinks or fewer per week; moderate drinkers, more than 3 and up to 14 drinks per week for men and more than 3 and up to 7 drinks per week for women; heavier drinkers, more than 14 drinks per week for men and more than 7 drinks per week for women, on average.
  • National Survey on Drug Use & Health (NSDUH)—Starting in 1999, NSDUH information about the frequency of the consumption of alcoholic beverages in the past 30 days has been obtained for all persons surveyed who are aged 12 and over. An extensive list of examples of the kinds of beverages covered is given to respondents prior to question administration. A drink is defined as a can or bottle of beer, a glass of wine or a wine cooler, a shot of liquor, or a mixed drink with liquor in it. Those times when the respondent had only a sip or two from a drink are not considered consumption. Alcohol use is based on the following questions: “During the past 30 days, on how many days did you drink one or more drinks of an alcoholic beverage?”, “On the days that you drank during the past 30 days, how many drinks did you usually have?”, and “During the past 30 days, on how many days did you have five or more drinks on the same occasion?”

Any-listed diagnosis

See Appendix II, Diagnosis.

Average annual rate of change (percent change)

In Health, United States, average annual rates of change, or growth rates, are calculated as follows:

[(Pn/Po)1/N − 1] × 100

where Pn = later time period

Po = earlier time period

N = number of years in interval.

This geometric rate of change assumes that a variable increases or decreases at the same rate during each year between the two time periods.

Average length of stay

In the National Hospital Discharge Survey, average length of stay is computed by dividing the total number of hospital days of care (counting the date of admission but not the date of discharge) by the number of patients discharged. The American Hospital Association computes average length of stay by dividing the number of inpatient days by the number of admissions. (Also see Appendix II, Days of care; Discharge; Inpatient.)

B

Basic actions difficulty

Basic actions difficulty captures limitations or difficulties in movement, emotional, sensory, or cognitive functioning associated with a health problem. Persons with more than one of these difficulties are counted only once in the estimates. The full range of functional areas cannot be assessed on the basis of National Health Interview Survey (NHIS) questions; however, the available questions can identify difficulty in the following core areas of functioning:

  • Movement (walking, standing, sitting, bending or kneeling, reaching overhead, grasping objects with fingers, and lifting).
  • Selected elements of emotional functioning, in particular, feelings that interfere with accomplishing daily activities. Respondents were classified based on responses to a series of questions that measure psychological distress.
  • Sensory functioning, based on difficulties seeing or hearing.
  • Selected elements in cognitive functioning, specifically difficulties with remembering, or experiencing confusion.

For many measures of disability, only disabilities resulting from an underlying condition that is chronic (based on nature and duration) are considered. However, whether the underlying conditions related to the core areas of basic actions difficulty were chronic was not a requirement in classifying persons. For more information on how this measure was constructed using NHIS data, including the specific questions asked, see: Altman B, Bernstein A. Disability and health in the United States, 2001–2005. Hyattsville, MD: NCHS; 2008. Available from: http://www.cdc.gov/nchs/data/misc/disability2001-2005.pdf.

(Also see Appendix II, Complex activity limitation; Hearing trouble.)

Bed, health facility

The American Hospital Association defines bed count as the number of beds, cribs, and pediatric bassinets that are set up and staffed for use by inpatients on the last day of the reporting period. In the Center for Medicare & Medicaid Service’s Online Survey Certification and Reporting (OSCAR) database, all beds in certified facilities are counted on the day of certification inspection. The Center for Mental Health Services of the Substance Abuse and Mental Health Services Administration counts the number of beds set up and staffed for use in inpatient and residential treatment services on the last day of the survey reporting period. (Also see Appendix II, Hospital; Occupancy rate.)

Binge drinking

Binge drinking is measured in the following data systems. (Also see Appendix II, Alcohol consumption.)

  • Monitoring the Future (MTF) Study—This school-based survey of secondary school students collects information on alcohol use by using self-completed questionnaires. To determine whether they have tried alcohol, students are asked a preliminary screening question: “Have you ever had any alcoholic beverage to drink—more than just a few sips?” Students who reply in the affirmative are then asked additional questions about their alcohol consumption, including one on binge drinking: “Think back over the last two weeks. How many times have you had five or more drinks in a row?” A drink is defined as a bottle of beer, a glass of wine, a shot glass of liquor, a mixed drink, etc. Information on binge drinking is obtained for high school seniors (starting in 1975) and for 8th and 10th graders (starting in 1991).
  • National Survey on Drug Use & Health (NSDUH)—In NSDUH, binge alcohol use is defined as “Five or more drinks on the same occasion (i.e., at the same time or within a couple of hours of each other) at least once in the past 30 days.” Heavy alcohol use is defined as “Five or more drinks on the same occasion (binge drinking) on at least 5 different days in the past 30 days.” (Also see Appendix II, Alcohol consumption.)

Birth cohort

A birth cohort consists of all persons born within a given period of time, such as a calendar year.

Birthweight

Birthweight is the first weight of the newborn obtained after birth. Low birthweight is defined as weighing less than 2,500 grams (5 lb 8 oz). Very low birthweight is defined as weighing less than 1,500 grams (3 lb 4 oz). Prior to 1979, low birthweight was defined as weighing 2,500 grams or less, and very low birthweight as weighing 1,500 grams or less.

Blood pressure, high

In Health, United States, a person is considered to have hypertension if they have measured high blood pressure (i.e., average measured systolic blood pressure of at least 140 mm Hg or diastolic pressure of at least 90 mm Hg) and/or if they report that they are taking a prescription medicine for high blood pressure (respondents were asked, “Are you now taking prescribed medicine for your high blood pressure?”), even if their blood pressure readings are within the normal range. Uncontrolled high blood pressure is defined as having an average measured systolic blood pressure of at least 140 mm Hg or diastolic pressure of at least 90 mm Hg, among those with hypertension. Those with uncontrolled high blood pressure also may be taking prescribed medicine for high blood pressure. These blood pressure standards are consistent with the following: National Heart, Lung, and Blood Institute. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. NIH pub no 04–5230. Bethesda, MD: National Institutes of Health; 2004. Available from: http://www.nhlbi.nih.gov/guidelines/hypertension/jnc7full.pdf. The Joint National Committee is currently updating its guidelines on high blood pressure.

Blood pressure data presented in Health, United States are from the National Health and Nutrition Examination Survey (NHANES). Blood pressure is measured by averaging up to three blood pressure readings taken for an NHANES participant. Blood pressure readings of 0 mm Hg are assumed to be in error and are not included in the estimates. The methods used to measure the blood pressure of participants have changed over the different NHANES survey years. Changes include the following:

  • Number of blood pressure measurements taken (increased from one to four).
  • Equipment maintenance procedures.
  • Training of persons taking readings (physician, nurse, or interviewer).
  • Proportion zero end-digits for systolic and diastolic readings.
  • Published diastolic definition.
  • Location where the measurements were taken [mobile examination center (MEC) or home].

In 1999 and subsequent years, blood pressure has been measured in the NHANES MEC by one of the MEC physicians. For people aged 8 and over, three consecutive blood pressure readings are obtained using the same arm. If a blood pressure measurement was interrupted or the measurer was unable to get one or more of the readings, a fourth attempt may be made. Both systolic and diastolic measurements are recorded to the nearest even number.

In NHANES III, three sets of blood pressure measurements were taken in the MEC for examinees aged 5 and over. Blood pressure measurements were also taken by trained interviewers during the household interview, on sample persons aged 17 and over. Systolic and diastolic average blood pressures were computed as the arithmetic mean of six or fewer measurements obtained at the household interview (maximum of three) and the MEC examination (maximum of three). If the examinee did not have blood pressure measurements taken in the MEC, this variable was calculated from measurements taken at the household interview. Both systolic and diastolic measurements were recorded to the nearest even number.

For more information on changes in blood pressure measurement in NHANES up to 1991, see: Burt VL, Cutler JA, Higgins M, Horan MJ, Labarthe D, Whelton P, et al. Trends in the prevalence, awareness, treatment, and control of hypertension in the adult U.S. population: Data from the health examination surveys, 1960 to 1991. Hypertension 1995;26(1):60–9.

Body mass index (BMI)

BMI is a measure that adjusts body weight for height. It is calculated as weight in kilograms divided by height in meters squared. Healthy weight for adults is defined as a BMI of 18.5 to less than 25; overweight (including obesity) is greater than or equal to 25; and obesity is greater than or equal to 30. Within the obesity category, Grade 1 obesity is defined as a BMI of 30.0 to less than 35.0; Grade 2 is 35.0 to less than 40.0; and Grade 3 is 40.0 or greater. The BMI variable on the data files, BMXBMI, is used to classify BMI in Health, United States. Prior to assigning a person to a BMI category, BMXBMI is rounded to one decimal place. BMI cut points are defined in the following: U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary guidelines for Americans, 2010, 7th ed. Washington, DC: U.S. Government Printing Office; 2010. Available from: http://www.cnpp.usda.gov/DGAs2010-PolicyDocument.htm; National Heart, Lung, and Blood Institute. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: The evidence report. NIH pub no 98–4083. Bethesda, MD: National Institutes of Health; 1998. Available from: http://www.nhlbi.nih.gov/guidelines/obesity/ob_gdlns.htm; and U.S. Department of Health and Human Services. Healthy people 2020: Nutrition, physical activity, and obesity; 2012. Available from: http://www.healthypeople.gov/2020/LHI/nutrition.aspx. The National Heart, Lung, and Blood Institute’s Expert Panel on Obesity is currently updating its report on overweight and obesity.

Obesity for children and adolescents is defined as a BMI at or above the sex- and age-specific 95th percentile BMI cut points from the 2000 CDC Growth Charts (http://www.cdc.gov/growthcharts/). Starting with Health, United States, 2010, the terminology describing excess weight among children changed from previous editions. The term obesity now refers to children who were formerly labeled as overweight. This is a change in terminology only and not a change in measurement. For more information, see: Ogden CL, Flegal KM. Changes in terminology for childhood overweight and obesity. National health statistics report; no 25. Hyattsville, MD: NCHS; 2010. Available from: http://www.cdc.gov/nchs/data/nhsr/nhsr025.pdf.

C

Cause of death

For the purpose of national mortality statistics, every death is attributed to one underlying condition, based on information reported on the death certificate and using the international rules for selecting the underlying cause of death from the conditions stated on the certificate. The underlying cause is defined by the World Health Organization (WHO) as “the disease or injury that initiated the train of events leading directly to death, or the circumstances of the accident or violence that produced the fatal injury.” Generally, more medical information is reported on death certificates than is directly reflected in the underlying cause of death. Conditions that are not selected as the underlying cause of death constitute the nonunderlying causes of death, also known as multiple cause of death.

Cause of death is coded according to the appropriate revision of the International Classification of Diseases (ICD) (Table III). Effective with deaths occurring in 1999, the United States began using the 10th revision of the ICD (ICD–10); during the period 1979–1998, causes of death were coded and classified according to the 9th revision (ICD–9). Table IV lists ICD codes for the 6th through 10th revisions for causes of death shown in Health, United States.

Each ICD revision has produced discontinuities in cause-of-death trends. These discontinuities are measured by using comparability ratios that are essential to the interpretation of mortality trends. For further discussion, see: http://www.cdc.gov/nchs/nvss/mortality/comparability_icd.htm.

[Also see Appendix II, Comparability ratio; International Classification of Diseases (ICD); and Appendix I, National Vital Statistics System (NVSS); Multiple Cause-of-Death File.]

Cause-of-death ranking

Selected causes of death of public health and medical importance are compiled into tabulation lists and are ranked according to the number of deaths assigned to these causes. The top-ranking causes determine the leading causes of death. Certain causes on the tabulation lists are not ranked if, for example, the category title represents a group title (such as “Major cardiovascular diseases” and “Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified”) or the category title begins with the words “Other” or “All other.” In addition, when one of the titles that represents a subtotal (such as “Malignant neoplasms”) is ranked, its component parts are not ranked. The tabulation lists used for ranking in the 10th revision of the International Classification of Diseases (ICD–10) include the List of 113 Selected Causes of Death, which replaces the ICD–9 List of 72 Selected Causes, HIV Infection and Alzheimer’s Disease; and the ICD–10 List of 130 Selected Causes of Infant Death, which replaces the ICD–9 List of 60 Selected Causes of Infant Death and HIV Infection. Causes that are tied receive the same rank; the next cause is assigned the rank it would have received had the lower-ranked causes not been tied, that is, a rank is skipped. For more information, see: Murphy SL, Xu J, Kochanek KD. Deaths: Final data for 2010. National vital statistics reports; vol 61 no 4. Hyattsville, MD: NCHS; 2012. Available from: http://www.cdc.gov/nchs/data/nvsr/nvsr61/nvsr61_4.pdf. [Also see Appendix II, International Classification of Diseases (ICD).]

Children’s Health Insurance Program (CHIP)

Title XXI of the Social Security Act, often referred to as the Children’s Health Insurance Program (CHIP), is a program originally enacted by the Balanced Budget Act of 1997. The Children’s Health Insurance Program Reauthorization Act of 2009 (CHIPRA, P.L. 111–3) reauthorized CHIP and appropriated funding for CHIP through FY 2013. The Patient Protection and Affordable Care Act of 2010 (ACA, P.L. 111–148) extends CHIP funding through FY 2015. CHIP provides federal funds for states to provide health care coverage to eligible low-income, uninsured children who do not qualify for Medicaid. Generally, CHIP is only available through age 18. However, there are a small number of adults covered with CHIP funds under waivers in a few states. CHIP gives states broad flexibility in program design within a federal framework that includes important beneficiary protections. Funds from CHIP may be used for a separate child health program or to expand Medicaid. Although CHIP is not part of Medicaid, in some instances in Health, United States, data on CHIP and Medicaid are presented together and those instances are discussed in the footnotes of the respective tables. For more information, see: http://www.medicaid.gov/Medicaid-CHIP-Program-Information/By-Topics/Childrens-Health-Insurance-Program-CHIP/CHIPRA.html. (Also see Appendix II, Health insurance coverage; Medicaid.)

Cholesterol

Serum total cholesterol is a combination of high-density lipoproteins (HDLs), low-density lipoproteins (LDLs), and very-low-density lipoproteins (VLDLs). High serum total cholesterol is a risk factor for cardiovascular disease. According to the National Cholesterol Education Program, high serum total cholesterol is defined as being greater than or equal to 240 mg/dL (6.20 mmol/L). Borderline high serum total cholesterol is defined as greater than or equal to 200 mg/dL and less than 240 mg/dL. Assessments of the components of total cholesterol, or lower thresholds for high total cholesterol, may be used for individuals with other risk factors for cardiovascular disease. For more information on high cholesterol guidelines, see: National Cholesterol Education Program (NCEP). Third report of the NCEP Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III): Final report. NIH pub no 02–5215. Bethesda, MD: National Institutes of Health, National Heart, Lung, and Blood Institute; 2002. Available from: http://www.nhlbi.nih.gov/guidelines/cholesterol/atp3full.pdf. The National Heart, Lung, and Blood Institute’s Adult Treatment Panel is currently updating its guidelines on high cholesterol.

In Health, United States, three measures of total cholesterol are presented: high cholesterol, high serum total cholesterol, and mean serum total cholesterol level. High cholesterol is based on both laboratory testing and self-reported medication use. It is defined as measured serum total cholesterol greater than or equal to 240 mg/dL or reporting taking cholesterol-lowering medications. Respondents answering “yes” to the question, “Are you now following this advice [from a doctor or health professional] to take prescribed medicine [to lower your cholesterol]?” were classified as taking cholesterol-lowering medications. High serum total cholesterol is defined as measured serum total cholesterol greater than or equal to 240 mg/dL (6.20 mmol/L). Mean serum total cholesterol level is based on serum samples collected during the National Health and Nutrition Examination Survey (NHANES) examination.

Venous blood serum samples collected from NHANES participants at mobile examination centers were frozen and shipped on dry ice to the laboratory conducting the lipid analyses. Serum total cholesterol was measured on all examined adults regardless of whether they had fasted, and data were analyzed regardless of fasting status. Cholesterol measurements are standardized according to the criteria of the CDC—and later the CDC–National Heart, Lung, and Blood Institute Cholesterol Standardization Program—to ensure comparable and accurate measurements. For more information, see: Myers GL, Cooper GR, Winn CL, Smith SJ. The Centers for Disease Control–National Heart, Lung, and Blood Institute Lipid Standardization Program: An approach to accurate and precise lipid measurements. Clin Lab Med 1989;9(1):105–35. A detailed summary of the procedures used for measurement of total cholesterol in the earlier NHANES survey years has been published in: Johnson CL, Rifkind BM, Sempos CT, Carroll MD, Bachorik PS, Briefel RR, et al. Declining serum total cholesterol levels among U.S. adults: The National Health and Nutrition Examination Surveys. JAMA 1993;269(23):3002–8. A description of the laboratory procedures for the total cholesterol measurement for different NHANES survey years is published by NCHS. Available from: http://www.cdc.gov/nchs/nhanes.htm.

Cigarette smoking

Cigarette smoking and related tobacco use are measured in the following data systems.

  • Birth file—With the 1989 revision of the U.S. Standard Certificate of Live Birth, information on cigarette smoking by the mother during pregnancy became available for the first time. Data from the 1989 revision are based on “yes/no” responses to the birth certificate item: “Other risk factors for this pregnancy: Tobacco use during pregnancy” and the average number of cigarettes per day with no specificity on timing during pregnancy. In 1989, 43 states and the District of Columbia (D.C.) collected data on tobacco use. The following states did not require the reporting of tobacco use in the standard format on the birth certificate: California, Indiana, Louisiana, Nebraska, New York, Oklahoma, and South Dakota. In 1990, information on tobacco use became available from Louisiana and Nebraska, increasing the number of reporting states to 45 and D.C. In 1991–1993, with the addition of Oklahoma to the reporting area, information on tobacco use was available for 46 states and D.C.; in 1994–1998, 46 states, D.C., and New York City reported tobacco use. In 1999, information on tobacco use became available from Indiana and New York, increasing the number of reporting states to 48 and D.C.; starting in 2000, with the addition of South Dakota, the reporting area included 49 states and D.C. During 1989–2006, California did not require the reporting of tobacco use. The area reporting tobacco use encompassed 87% of U.S. births in 1999–2002.
    Beginning in 2003, some states implemented the 2003 revision of the U.S. Standard Certificate of Live Birth, which asked for the number of cigarettes smoked at different intervals before and during pregnancy. Data on mother’s tobacco use during pregnancy from the 2003 revision of the birth certificate are not comparable with data from the 1989 revision. Therefore, in Health, United States, 2012, 2009, and 2010 data on cigarette smoking are shown only for the 25 states that used the 2003 revision in 2009 and 2010, in order to provide 2 years of comparable data. The 25 states that used the 2003 revision of the U.S. Standard Certificate of Live Birth for data on mother’s tobacco use by January 1, 2009, were California, Colorado, Delaware, Idaho, Indiana, Iowa, Kansas, Kentucky, Montana, Nebraska, New Hampshire, New Mexico, New York (including New York City), North Dakota, Ohio, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Washington state, and Wyoming. For more information on this topic, refer to the annual series of “Births: Final Data” reports, available from the National Vital Statistics System website at: http://www.cdc.gov/nchs/nvss.htm.
  • Monitoring the Future (MTF) Study—Information on current cigarette smoking was obtained for high school seniors (starting in 1975) and for 8th and 10th graders (starting in 1991), based on the following question: “How frequently have you smoked cigarettes during the past 30 days?”
  • National Health Interview Survey (NHIS)—Information about cigarette smoking is obtained for adults aged 18 and over. Starting in 1993, current smokers are identified by asking the following two questions: “Have you smoked at least 100 cigarettes in your entire life?” and “Do you now smoke cigarettes every day, some days, or not at all?” Persons who smoked 100 cigarettes and who now smoke every day or some days were defined as current smokers. Before 1992, current smokers were identified based on positive responses to the following two questions: “Have you smoked 100 cigarettes in your entire life?” and “Do you smoke now?” (traditional definition). In 1992, the definition of current smoker in NHIS was modified to specifically include persons who smoked on some days (revised definition). In 1992, cigarette smoking data were collected for a half-sample with half the respondents (one-quarter sample) using the traditional smoking questions and the other half of respondents (one-quarter sample) using the revised smoking question (“Do you smoke every day, some days, or not at all?”). An unpublished analysis of the 1992 traditional smoking measure revealed that the crude percentage of current smokers aged 18 and over remained the same as for 1991. The estimates for 1992 shown in Health, United States combine data collected using both the traditional and revised questions.
    In 1993–1995, estimates of cigarette smoking prevalence were based on a half-sample. Smoking data were not collected in 1996. Starting in 1997, smoking data were collected in the Sample Adult questionnaire. For more information on survey methodology and sample sizes pertaining to NHIS cigarette smoking data, see the NHIS tobacco information website at: http://www.cdc.gov/nchs/nhis/tobacco.htm.
  • National Survey on Drug Use & Health (NSDUH)— Information on current cigarette smoking is obtained for all persons surveyed who are aged 12 and over, based on the following question: “During the past 30 days, have you smoked part or all of a cigarette?”

Civilian noninstitutionalized population; Civilian population

See Appendix II, Population.

Colorectal tests or procedures

Colorectal tests or procedures are used to detect polyps, abnormal cell growth, lesions, and other gastrointestinal conditions, including colon cancer. In the National Health Interview Survey (NHIS), questions about colorectal tests or procedures were asked on an intermittent schedule.

In 2000, 2003, 2005, and 2008, respondents aged 40 and over were asked, “Have you ever had a sigmoidoscopy, colonoscopy, or proctoscopy?” In 2010, the questionnaire was redesigned and the aforementioned question was divided into two separate questions: “Have you ever had a colonoscopy?” and “Have you ever had a sigmoidoscopy?” An additional question about colorectal testing, “Have you ever had a blood stool test using a home testing kit?” was asked in each of these survey years.

Respondents who replied that they had a colorectal test or procedure were asked subsequent questions about the month, year, and time since their most recent test or procedure. In 2000 and 2003, if respondents did not provide the year of, or the time since, their most recent colorectal exam, they were asked about the time frame of their most recent exam (i.e., whether they had the exam a year ago or less, more than 1 year ago but not more than 2 years ago, more than 2 years ago but not more than 3 years ago, more than 3 years ago but not more than 5 years ago, more than 5 years ago but not more than 10 years ago, or over 10 years ago). For adults who provided the year, but not the month, of their most recent exam, the exam date was coded as July 15 of the provided year.

In 2005, 2008, and 2010, the questionnaire pattern was modified so that respondents giving an incomplete or partial date (missing month or year) of their most recent colorectal exam were asked a follow-up question about the time since their most recent exam (i.e., whether they had the exam a year ago or less, more than 1 year ago but not more than 2 years ago, more than 2 years ago but not more than 3 years ago, more than 3 years ago but not more than 5 years ago, more than 5 years ago but not more than 10 years ago, or over 10 years ago). Because of this additional probing when the month of exam was not provided, there was no need to code the missing data on the month of the most recent exam as July 15 of the provided year in order to determine the time frame since the most recent colorectal procedure.

In Health, United States, colorectal tests or procedures include reports of a home fecal occult blood test (FOBT) in the past year, a sigmoidoscopy procedure in the past 5 years with FOBT in the past 3 years, or a colonoscopy in the past 10 years.

Colorectal screening tests and procedures may be used for diagnostic or screening purposes. Recommendations for screening tests and time between screening varies based on individual risks and the particular colorectal tests. For a summary of current colorectal screening recommendations, see the U.S. Preventive Services Task Force summary of recommendations on screening for colorectal cancer. Available from: http://www.uspreventiveservicestaskforce.org/uspstf/uspscolo.htm.

Community hospital

See Appendix II, Hospital.

Comparability ratio

About every 10 to 20 years, the International Classification of Diseases (ICD) is revised to stay abreast of advances in medical science and changes in medical terminology. Each of these revisions produces breaks in the continuity of cause-of-death statistics because of changes in classification and in the rules for selecting an underlying cause of death. Classification and rule changes affect cause-of-death trend data by shifting deaths away from some cause-of-death categories and into others. Comparability ratios measure the effect of changes in classification and coding rules. For the causes shown in Table V, comparability ratios range between 0.6974 and 1.0365. Influenza and pneumonia had the lowest comparability ratio (0.6974), indicating that this cause is about 30% less likely to be selected as the underlying cause of death under ICD–10 than under ICD–9. Unintentional poisoning had the highest comparability ratio (1.0365), indicating that unintentional poisoning is more than 3% more likely to be selected as the underlying cause when ICD–10 coding is used.

For selected causes of death, the ICD–9 codes used to calculate death rates for 1980–1998 differ from the ICD–9 codes most nearly comparable with the corresponding ICD–10 cause-of-death category, which also affects the ability to compare death rates across ICD revisions. Examples of these causes are Ischemic heart disease; Cerebrovascular diseases; Trachea, bronchus, and lung cancer; Unintentional injuries; and Homicide. To address this source of discontinuity, mortality trends for 1980–1998 were recalculated using ICD–9 codes that are more comparable with codes for corresponding ICD–10 categories. Table IV shows the ICD–9 codes used for these causes. This modification may lessen the discontinuity between the 9th and 10th revisions, but the effect on the discontinuity between the 8th and 9th revisions is not measured.

Comparability ratios shown in Table V are based on a comparability study in which the same deaths were coded using both the 9th and 10th revisions. The comparability ratio was calculated by dividing the number of deaths classified by ICD–10 by the number of deaths classified by ICD–9. The resulting ratios represent the net effect of the 10th revision on cause-of-death statistics and can be used to adjust mortality statistics for causes of death classified by the 9th revision to be comparable with cause-specific mortality statistics classified by the 10th revision.

The application of comparability ratios to mortality statistics helps make the analysis of change between 1998 and 1999 more accurate and complete. The 1998 comparability-modified death rate is calculated by multiplying the comparability ratio by the 1998 death rate. Comparability-modified rates should be used to estimate mortality change between 1998 and 1999.

Caution should be used when applying the comparability ratios presented in Table V to age-, race-, and sex-specific mortality data. Demographic subgroups may sometimes differ with regard to their cause-of-death distribution, and this would result in demographic variation in cause-specific comparability ratios.

For more information, see: Anderson RN, Miniño AM, Hoyert DL, Rosenberg HM. Comparability of cause of death between ICD–9 and ICD–10: Preliminary estimates. National vital statistics reports; vol 49 no 2. Hyattsville, MD: NCHS; 2001; Kochanek KD, Smith BL, Anderson RN. Deaths: Preliminary data for 1999. National vital statistics reports; vol 49 no 3. Hyattsville, MD: NCHS; 2001; Final ratios for 113 selected causes of death. Available from: ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Datasets/Comparability/icd9_icd10/; and the ICD comparability ratio website at: http://www.cdc.gov/nchs/nvss/mortality/comparability_icd.htm. [Also see Appendix II, Cause of death; International Classification of Diseases (ICD).]

Complex activity limitation

Complex activity limitation is a construct used to measure disability as defined by the inability to function successfully in certain social roles. Complex activities consist of the tasks and organized activity that make up numerous social roles such as working, maintaining a household, living independently, or participating in community activities. Complex activity performance requires the execution of a combination of core areas of functioning. Complex activities include the following:

  • Maintaining independence, including self-care and the ability to carry out activities associated with maintaining a household, such as shopping, cooking, and taking care of bills [measures are based on questions commonly known as activities of daily living (ADLs) and instrumental activities of daily living (IADLs)]. Limitations in these activities usually reflect severe restrictions and are associated with limitations in other complex activities.
  • Difficulties experienced with social and leisure activities—represented in this measure by using questions about attending movies or sporting events, visiting with friends, or pursuing hobbies or relaxation activities.
  • Perceived limitation in the ability to work (a core aspect of social participation for the majority of the U.S. population)—represented by the respondent’s self-defined limitation in the kind or amount of work they can do or their inability to work at a job or business.

For many measures of disability, only disabilities resulting from an underlying condition that is chronic (based on nature and duration) are considered. However, whether the underlying conditions related to the complex activities were chronic was not a requirement in classifying persons as having a complex activity limitation. For more information on how this measure was constructed using data from the National Health Interview Survey, including the specific questions asked, see: Altman B, Bernstein A. Disability and health in the United States, 2001–2005. Hyattsville, MD: NCHS; 2008. Available from: http://www.cdc.gov/nchs/data/misc/disability2001-2005.pdf. [Also see Appendix II, Activities of daily living (ADL); Basic actions difficulty; Instrumental activities of daily living (IADL).]

Computed tomography (CT) scanner

A CT, or computed axial tomography (CAT), scanner is an x-ray machine that combines many x-ray images, with the aid of a computer, to generate cross-sectional views and, if needed, three-dimensional images of the internal organs and structures of the body.

Consumer Price Index (CPI)

The CPI, prepared by the U.S. Bureau of Labor Statistics, is a monthly measure of the average change in prices of goods and services purchased by urban households. The medical care component of the CPI shows trends in medical care prices based on specific indicators of hospital, medical, and drug prices. A revised definition of the CPI has been in use since January 1988. [Also see Appendix II, Gross domestic product (GDP); Health expenditures, national; and Appendix I, Consumer Price Index (CPI).]

Contraception

The National Survey of Family Growth collects information on contraceptive use during heterosexual vaginal intercourse, as reported by women aged 15–44. For current contraceptive use, women were asked about contraceptive use during the month of interview. Women were classified by whether they reported using any of 19 methods of contraception at any time in the month of interview. Contraceptive methods listed as “other methods” in 2006–2008 included the contraceptive ring, female condom/vaginal pouch, foam, cervical cap, Today-brand sponge, suppository or insert, jelly or cream (without diaphragm), and other methods. Previously, contraceptive methods listed as “other methods” included the following: for 2002, the female condom, foam, cervical cap, Today sponge, suppository or insert, jelly or cream (without diaphragm), or other method; for 1995, the female condom or vaginal pouch, foam, cervical cap, Today sponge, suppository or insert, jelly or cream, or other method; for 1988, foam, douche, Today sponge, suppository or insert, jelly or cream, or other method; and for 1982, foam, douche, suppository or insert, or other method.

Cost-charge ratio

The Agency for Healthcare Research and Quality’s Healthcare Cost and Utilization Project (HCUP) contains data on total charges per discharge as reported on the hospital discharge record. This charge information represents the amount the hospital billed for services but does not reflect how much hospital services actually cost or the specific amounts that hospitals received in payment. Data on costs may be of more interest to some users. The HCUP Cost-to-Charge Ratio Files convert charges to costs. Each file contains hospital-specific cost-to-charge ratios based on all-payer inpatient cost for nearly every hospital in HCUP. Cost information was obtained from hospital accounting reports collected by the Centers for Medicare & Medicaid Services. Some imputations for missing values were necessary. These files are unique by year.

Critical access hospital

See Appendix II, Hospital.

D

Days of care

Days of care is defined similarly in several data systems, as discussed below. (Also see Appendix II, Admission; Average length of stay; Discharge; Hospital; Hospital utilization; Inpatient.)

  • American Hospital Association—Days, hospital days, or inpatient days are the number of adult and pediatric days of care rendered during the entire reporting period. Days of care for newborns are excluded.
  • National Hospital Discharge Survey (NHDS)—Days of care refers to the total number of patient days accumulated by inpatients at the time of discharge from nonfederal short-stay hospitals during a reporting period. All days from and including the date of admission, but not including the date of discharge, are counted.

Dental caries

Dental caries is evidence of dental decay on any surface of a tooth. The condition of untreated dental caries was identified by an oral examination as part of the National Health and Nutrition Examination Survey (NHANES). In Health, United States, data on dental caries for 2001–2004 and earlier are based on an examination conducted by a trained dentist. Untreated dental caries refers to coronal caries, that is, caries on the crown or enamel surface of the tooth. Treated dental caries and root caries are not included. As part of NHANES, study participants aged 2 years and over were eligible for the examination, as long as they did not meet other exclusion criteria. Both permanent and primary (baby) teeth were evaluated, depending on the age of the participant. For children aged 2–5, only caries in primary teeth was included. For children aged 6–11, caries in both primary and permanent teeth was included. For children aged 12 and over, and for adults, only caries in permanent teeth was included. Starting with 2005–2006 NHANES data, data on dental caries were collected using the Basic Screening Examination (BSE), a simplified screening process to collect information on untreated caries, dental restorations, and dental sealants. BSE differs from previous NHANES oral health protocols because it does not assess each tooth surface, the assessments are not made by a dentist, and the presence of dental caries on primary or permanent teeth cannot be distinguished in the data set. Dental caries and other oral health surveillance data are collected by a health technologist on examined persons aged 5 and over for 2005–2008 data and persons aged 3–19 for 2009–2010 data. In Health, United States, only dental caries on 28 teeth was considered; the third molars were excluded. Because of this change in the examination process and because 2005–2010 dental caries data are based on both primary and permanent teeth, regardless of age, data for 2005–2010 need to be interpreted with caution, especially when comparing with earlier data. For more information, see: Dye BA, Barker LK, Li X, Lewis BG, Beltrán-Aguilar ED. Overview and quality assurance for the oral health component of the National Health and Nutrition Examination Survey (NHANES), 2005–08. J Public Health Dent 2011;71(1):54–61.

For more information, see: http://www.cdc.gov/nchs/data/nhanes/nhanes_05_06/ohx_d.pdf, http://www.cdc.gov/nchs/nhanes/nhanes2007-2008/OHX_E.htm, and http://www.cdc.gov/nchs/nhanes/nhanes2009-2010/OHXDEN_F.htm.

Dental visit

Starting in 1997, National Health Interview Survey respondents were asked, “About how long has it been since you last saw or talked to a dentist? Include all types of dentists, such as orthodontists, oral surgeons, and all other dental specialists as well as hygienists.” Starting in 2001, the question was modified slightly to ask respondents how long it had been since they last saw a dentist. Questions about dental visits were not asked for children under age 2 for years 1997–1999 and under age 1 for years 2000 and beyond. Starting with 1997 data, estimates are presented for people with a dental visit in the past year. Prior to 1997, dental visit estimates were based on a 2-week recall period.

Diabetes

Diabetes is a group of conditions in which insulin is not adequately secreted or utilized. Diabetes is a leading cause of disease and death in the United States. Using data from the National Health and Nutrition Examination Survey (NHANES), three measures of diabetes are presented in Health, United States: physician-diagnosed diabetes, undiagnosed diabetes, and total diabetes. Physician-diagnosed diabetes data were obtained by self-report and exclude women who reported having diabetes only during pregnancy. Respondents who answered “yes” to the question, “Other than during pregnancy, have you ever been told by a doctor or health professional that you have diabetes or sugar diabetes?” were classified as having physician-diagnosed diabetes.

Only respondents who were not classified as having physician-diagnosed diabetes were evaluated to determine if they had undiagnosed diabetes. Undiagnosed diabetes was based on the results of laboratory testing of whole blood and blood plasma samples collected from NHANES participants at mobile examination centers. Undiagnosed diabetes was defined as a fasting plasma glucose (FPG) of at least 126 mg/dL or a hemoglobin A1c of at least 6.5% and no reported physician diagnosis. Respondents had fasted for at least 8 hours and less than 24 hours at the time of the blood draw. Fasting is not necessary to measure hemoglobin A1c. However, to be consistent with the subsample of fasting respondents used for FPG, assessment of undiagnosed diabetes in Health, United States is limited to the fasting subsample.

Starting with Health, United States, 2010, an elevated hemoglobin A1c (greater than or equal to 6.5%) was included as a component of the definition of undiagnosed diabetes, along with FPG. Previous editions of Health, United States did not evaluate hemoglobin A1c to classify respondents as having undiagnosed diabetes; undiagnosed diabetes was based solely on elevated FPG (greater than or equal to 126 mg/dL) among those without physician-diagnosed diabetes. The revised definition of undiagnosed diabetes was based on recommendations from the American Diabetes Association (ADA). Hemoglobin A1c was recommended as a component in diagnosing diabetes because recent improvements in assay standardization make A1c results more reliable. In addition, research has provided evidence linking elevated A1c levels with diabetic complications, thus allowing for a threshold to be set above which patients would be diagnosed as having diabetes. Although the ADA recommends using hemoglobin A1c greater than or equal to 6.5% as an indicator of undiagnosed diabetes, it cautions that A1c may be misleading in individuals with certain blood disorders (including sickle cell trait), which may have specific ethnic or geographic distributions. Therefore, clinicians may use other criteria and tests to diagnose a specific patient. For more information, see: Diagnosis and classification of diabetes mellitus. Diabetes Care 2013;36(suppl 1):S67–S74; Standards of medical care in diabetes—2010. Diabetes Care 2010;33(suppl 1):S11–S61; and International expert committee report on the role of the A1c assay in the diagnosis of diabetes. Diabetes Care 2009;32(7):1327–34. To ensure data comparability over time, the revised definition of undiagnosed diabetes was applied to all estimates shown in Health, United States. As expected, this revised definition increased the percentage of respondents classified as having undiagnosed diabetes.

Prevalence estimates of undiagnosed diabetes among those aged 20 and over in 1988–1994 increased from 2.7% to 3.3% using the new definition, and total diabetes prevalence increased from 7.8% to 8.4%. Among men, the prevalence using the new definition increased from 3.0% to 3.7%, and among women it increased from 2.4% to 3.0%. The prevalence for non-Hispanic white persons increased from 2.5% to 2.8%, for non-Hispanic black persons from 3.4% to 6.0%, and for Mexican persons from 3.4% to 4.1%. Increases in the prevalence of undiagnosed diabetes by age group were from 0.8% to 1.0% among those aged 20–44, from 5.0% to 6.0% among those aged 45–64, and from 5.6% to 6.7% among those aged 65 and over.

For 2005–2006, the prevalence of undiagnosed diabetes among those aged 20 and over increased from 2.5% to 3.0% using the new definition, and total diabetes prevalence increased from 10.3% to 10.7%. Among men, the prevalence of undiagnosed diabetes increased from 3.5% to 4.0%, and among women it increased from 1.7% to 2.0%. The prevalence for non-Hispanic white persons increased from 2.6% to 2.9%, for non-Hispanic black persons from 2.5% to 3.4%, and for persons of Mexican origin from 3.0% to 3.6%. Increases by age group were from 0.9% to 1.1% among those aged 18–44, from 3.0% to 3.5% among those aged 45–64, and from 6.4% to 7.3% among those aged 65 and over.

Periodically, NHANES laboratory testing is performed at different laboratories and using different instruments than testing in earlier years. In those instances, NHANES conducts crossover studies to evaluate the impact of these changes on laboratory measurements, and thus their impact on the evaluation of data over time. Crossover studies have been conducted to evaluate the impact of laboratory changes on both FPG and A1c. The recommended adjustments to FPG to account for laboratory changes from 2005–2006 to present have been incorporated in estimates presented in Health, United States so that these estimates are compatible with those from earlier years.

At the time the 2005–2006 data were released, NHANES recommended that 2005–2006 data of A1c measurements be adjusted to be compatible with earlier years. Adjusted estimates were presented in prior editions of Health, United States. After additional evaluation of the A1c data, in November 2011 NHANES changed its guidance and recommended no adjustments to the 2005–2006 and subsequent A1c data. Estimates shown in Health, United States, 2012 are produced without any correction factor applied to A1c data. Implementation of this new guidance caused no change in the percentage of adults with diabetes (total, physician-diagnosed, and undiagnosed). Estimates of poor glycemic control among persons with diagnosed diabetes changed between 0.0 and 1.0 percentage point.

For more information, see: http://www.cdc.gov/nchs/data/nhanes/A1c_webnotice.pdf, and http://www.cdc.gov/nchs/data/nhanes/nhanes_05_06/glu_d.pdf, and http://www.cdc.gov/nchs/data/nhanes/nhanes_05_06/ghb_d.pdf.

Total diabetes includes those who were classified as having either physician-diagnosed or undiagnosed diabetes. Prevalence estimates of total diabetes increased using the new definition of undiagnosed diabetes.

Diagnosis

Diagnosis is the act or process of identifying or determining the nature and cause of a disease or injury through evaluation of patient history, examination, and review of laboratory data. Diagnoses in the National Hospital Discharge Survey, the National Ambulatory Medical Care Survey, and the National Hospital Ambulatory Medical Care Survey are abstracted from medical records and coded to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD–9–CM). For a given medical care encounter, the first-listed diagnosis can be used to categorize the visit, or if more than one diagnosis is recorded on the medical record, the visit can be categorized based on all diagnoses recorded. Analyzing first-listed diagnoses avoids double-counting events such as visits or hospitalizations; the first-listed diagnosis is often, but not always, considered the most important or dominant condition among all comorbid conditions. However, the choice of the first-listed diagnosis by the medical facility may be influenced by reimbursement or other factors. A hospital discharge would be considered a first-listed stroke discharge if the ICD–9–CM diagnosis code for stroke was recorded in the first diagnosis field on the hospital record. An any-listed stroke discharge would classify all diagnoses of stroke recorded on the hospital face sheet, regardless of the order in which they are listed. Any-listed diagnoses double-count events such as visits or hospitalizations with more than one recorded diagnosis but provide information on the burden a specific diagnosis presents to the health care system. (Also see Appendix II, External cause of injury; Injury; Injury-related visit.)

Diagnostic and other nonsurgical procedure

See Appendix II, Procedure.

Discharge

The National Health Interview Survey defines a hospital discharge as the completion of any continuous period of stay of one night or more in a hospital as an inpatient. According to the National Hospital Discharge Survey and the Healthcare Cost and Utilization Project—Nationwide Inpatient Sample, a discharge is a completed inpatient hospitalization. A hospitalization may be completed by death or by release of the patient to the customary place of residence, a nursing home, another hospital, or other locations. (Also see Appendix II, Admission; Average length of stay; Days of care; Inpatient.)

Drug

Drugs are pharmaceutical agents, by any route of administration, for the prevention, diagnosis, or treatment of medical conditions or diseases. Data on specific drug use are collected in several NCHS surveys. (Also see Appendix II, Multum Lexicon Plus therapeutic class.)

  • National Health and Nutrition Examination Survey (NHANES)—Drug information from NHANES III and from NHANES from 1999 through 2010 was collected during an in-person interview conducted in the participant’s home. Starting with 2001 data, participants were asked whether they had taken a medication in the past 30 days for which they needed a prescription. For 1999–2000 and 1988–1994 data, the question wording differed slightly; participants were asked whether they had taken a prescription medication in the past month. For all survey years, those who answered “yes” were asked to provide the prescription medication containers for the interviewer. For each medication reported, the interviewer entered the product’s complete name from the container. If no container was available, the interviewer asked the participant to verbally report the name of the medication. In addition, participants were asked how long they had been taking the medication and the main reason for use.
    All reported medication names were converted to their standard generic ingredient name. For multi-ingredient products, the ingredients were listed in alphabetical order and counted as one drug (e.g., Tylenol #3 was listed as acetaminophen; codeine). No trade or proprietary names were provided on the data file..
    Drug data from NHANES provide a snapshot of all prescribed drugs reported by a sample of the civilian noninstitutionalized population for a 30-day period (or past month, for earlier survey years). Drugs taken on an irregular basis, such as every other day, once per week, or for a 10-day period, were captured in the 30-day recall period. Data shown inHealth, United States for the percentage of the population reporting multiple prescription drugs during the past 30 days include a range of drug utilization patterns; for example, persons who took three or more drugs daily during the past 30 days or persons who took a different drug three separate times would be classified as taking three or more drugs in the past 30 days, as long as at least three different drugs were taken at some time during the past 30 days.
    For more information on prescription drug data collection and coding in NHANES, see: http://www.cdc.gov/nchs/nhanes/nhanes1999-2000/RXQ_DRUG.htm.
    For more information on NHANES III prescription drug data collection and coding, see: ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/nhanes/nhanes3/2A/pupremed.pdf. [Also see Appendix I, National Health and Nutrition Examination Survey (NHANES).]

E

Education

Several approaches to defining educational categories are used in Health, United States.

  • Birth file—Information on educational attainment of the mother is based on number of years of school completed, as reported by the mother on the birth certificate. Between 1970 and 1992, the reporting area for maternal education expanded.
    Mother’s education was reported on the birth certificate by 38 states in 1970. Data were not available from Alabama, Arkansas, California, Connecticut, Delaware, the District of Columbia (D.C.), Georgia, Idaho, Maryland, New Mexico, Pennsylvania, Texas, and Washington state. In 1975, these data became available from Connecticut, Delaware, Georgia, Maryland, and D.C., increasing the number of states reporting mother’s education to 42 and D.C. Between 1980 and 1988, only three states— California, Texas, and Washington—did not report mother’s education. In 1988, mother’s education was also missing for New York state outside New York City. In 1989–1991, mother’s education was missing only from Washington state and New York state outside New York City. During 1992–2002, mother’s education was reported by all 50 states and D.C.
    Starting in 2003, some states implemented the 2003 revision of the U.S. Standard Certificate of Live Birth. The education item on the 2003 revision asks for the highest degree or level of school completed, whereas the education item on the 1989 revision asks for highest grade completed. Data on mother’s education from the 2003 revision of the birth certificate are not comparable with data from the 1989 revision. For more information on this topic, refer to the annual series of “Births: Final Data” reports, available from the National Vital Statistics System website at: http://www.cdc.gov/nchs/nvss.htm.
  • National Health Interview Survey (NHIS)—Starting in 1997, the NHIS questionnaire was changed to ask, “What is the highest level of school [person] has completed or the highest degree received?” Responses were used to categorize adults according to educational credentials [i.e., no high school diploma or general educational development high school equivalency diploma (GED); high school diploma or GED; some college, no bachelor’s degree; bachelor’s degree or higher].
    Prior to 1997, the education variable in NHIS was measured by asking, “What is the highest grade or year of regular school [person] has ever attended?” and “Did [person] finish the grade/year?” Responses were used to categorize adults according to years of education completed (i.e., less than 12, 12, 13–15, or 16 years or more).
    Data from the 1996 and 1997 NHIS were used to compare distributions of educational attainment for adults aged 25 and over, using categories based on educational credentials (1997) and categories based on years of education completed (1996). A larger percentage of persons reported some college than 13–15 years of education, and a correspondingly smaller percentage reported high school diploma or GED than 12 years of education. In 1997, 19% of adults reported no high school diploma, 31% a high school diploma or GED, 26% some college, and 24% a bachelor’s degree or higher. In 1996, 18% of adults reported less than 12 years of education, 37% reported 12 years, 20% reported 13–15 years, and 25% reported 16 or more years of education.
  • National Health and Nutrition Examination Survey (NHANES)—In 1988–1994 (NHANES III) the questionnaire asked, “What is the highest grade or year of regular school [person] has completed?” Responses were used to categorize adults according to educational credentials [i.e., no high school diploma or general educational development high school equivalency diploma (GED); high school diploma or GED; some college, no bachelor’s degree; bachelor’s degree or higher]. Starting with 1999–2000 data, the questionnaire was changed to ask, “What is the highest grade or level of school (you have/[person] has) completed or the highest degree (you have/[person] has) received?” For data on children, education is based on the level of education completed by the head of the household. The question asked is, “What is the highest grade or level of school (you have/[person] has) completed or the highest degree (you have/[person] has) received?”

Emergency department

According to the National Hospital Ambulatory Medical Care Survey, an emergency department is a hospital facility that is staffed 24 hours a day and provides unscheduled outpatient services to patients whose condition requires immediate care. Emergency services provided under the “hospital as landlord” arrangement were also eligible. An emergency department was in scope if it was staffed 24 hours a day. If an in-scope emergency department had an emergency service area that was open less than 24 hours a day, then that area was included under the emergency department. If a hospital had an emergency department that was staffed less than 24 hours a day, that department was considered an outpatient clinic. (Also see Appendix II, Emergency department or emergency room visit; Outpatient department.)

Emergency department or emergency room visit

Starting with the 1997 National Health Interview Survey, respondents to the Sample Adult questionnaire and the Sample Child questionnaire (generally a parent) were asked about the number of visits to hospital emergency rooms during the past 12 months, including visits that resulted in hospitalization. In the National Hospital Ambulatory Medical Care Survey, an emergency department visit is a direct personal exchange between a patient and a physician or other health care provider working under the physician’s supervision, for the purpose of seeking care and receiving personal health services. (Also see Appendix II, Emergency department; Injury-related visit.)

Employer costs for employee compensation

Employer costs for employee compensation is a measure of the average cost, per employee hour worked, to employers for wages, salaries, and benefits. Wages and salaries are defined as the hourly straight-time wage rate or, for workers not paid on an hourly basis, straight-time earnings divided by the corresponding hours. Straight-time wage and salary rates are total earnings before payroll deductions, excluding premium pay for work in addition to the regular work schedule (e.g., overtime, weekends, and holidays), shift differentials, and nonproduction bonuses such as discretionary holiday bonuses and lump-sum payments provided in lieu of wage increases. Production bonuses, incentive earnings, commission payments, and cost-of-living adjustments are included in straight-time wage and salary rates. Benefits covered are paid leave (paid vacations, holidays, sick leave, and other leave), supplemental pay (premium pay for overtime, weekends, or holidays), shift differentials, nonproduction bonuses, insurance benefits (life, health, and short- and long-term disability), retirement and savings benefits (pension and other retirement plans and savings and thrift plans), and legally required benefits (Social Security, Medicare, federal and state unemployment insurance, and workers’ compensation). As of June 2006, the “other benefits” category, which included severance pay and supplemental unemployment benefits, was eliminated from survey collection. As of June 2008, “other leave benefit” includes only paid personal leave. [Also see Appendix I, National Compensation Survey (NCS).]

End-stage renal disease (ESRD)

ESRD is a complete or near-complete failure of the kidneys to function to excrete wastes, concentrate urine, and regulate electrolytes. ESRD occurs when the kidneys are no longer able to function at the level necessary for day-to-day life. It usually occurs as chronic renal failure worsens to the point where kidney function is less than 10% of normal. At that point, kidney function is so low that without dialysis or kidney transplantation, complications are multiple and severe, and death will occur from accumulation of fluids and waste products in the body. Without treatment, the loss of kidney function in ESRD is usually irreversible and permanent, and death follows.

Although the Medicare program covers the majority of ESRD-certified patients, not all individuals with ESRD are eligible for Medicare. In addition to being medically determined to have ESRD, filing an application, and meeting any applicable waiting period, an individual must meet one of the following criteria:

  • The individual has earned the required work credits under Social Security, Railroad Retirement, or as a government employee.
  • The individual is receiving Social Security or Railroad Retirement benefits.
  • The individual is the spouse or dependent child of a person who has earned the required work credits or is receiving Social Security or Railroad Retirement benefit.

The United States Renal Data System has tracked both Medicare-eligible and -ineligible ESRD patients since May 1995. For more information, see Appendix I, United States Renal Data System (USRDS).

External cause of injury

The external cause of injury is used for classifying the circumstances in which injuries occur. The International Classification of Diseases, 9th Revision (ICD–9), External Cause of Injury Matrix, is a two-dimensional array describing both the mechanism or external cause of the injury (e.g., fall, motor-vehicle traffic) and the manner or intent of the injury (e.g., unintentional, self-inflicted, or assault). Although this matrix was originally developed for mortality, it has been adapted for use with the ICD–9 Clinical Modification (ICD–9–CM). For more information, see the NCHS website at: http://www.cdc.gov/nchs/injury/injury_tools.htm; and see: Bergen G, Chen LH, Warner M, Fingerhut LA. Injury in the United States: 2007 chartbook. Hyattsville, MD: NCHS; 2008. Available from: http://www.cdc.gov/nchs/data/misc/injury2007.pdf.

F

Family income

For the National Health Interview Survey and the National Health and Nutrition Examination Survey, all people within a household who are related to each other by blood, marriage, or adoption constitute a family. Each member of a family is classified according to the total income of the family. Unrelated individuals are classified according to their own income. For the National Survey of Children’s Health, multiple families could live in a child’s household, but the survey does not explicitly define the term “family” to the respondents. The respondents can answer about the health and health care of the child if they live in the child’s household. The total income of the family is derived from the total combined income for all members in the child’s household.

  • National Health Interview Survey (NHIS)—Prior to 1997, family income was the total income received by members of a family (or by an unrelated individual) in the 12 months before interview. Family income included wages, salaries, rents from property, interest, dividends, profits and fees from their own businesses, pensions, and help from relatives. Starting in 1997, NHIS collected family income data for the calendar year prior to interview (e.g., 2011 family income data were based on calendar year 2010 information). The 1997–2006 instrument allowed the respondent to supply a specific dollar amount (up to $999,995). Any family income responses greater than $999,995 were entered as $999,996. Respondents who did not know or refused to give a dollar amount in response to this question were asked if their total combined family income for the previous year was $20,000 or more, or less than $20,000. If the respondent answered this question, he or she was then given one of two flash cards and asked to indicate which income group listed on the card best represented the family’s combined income during the previous calendar year. One flash card listed incomes that were $20,000 or more, and the other flash card listed incomes that were less than $20,000. Starting with the 2007 NHIS, the income amount follow-up questions that had been in place since 1997 were replaced with a series of unfolding bracket questions. The unfolding bracket method asked a series of closed-ended income range questions (e.g., “Is it less than $50,000?”) if the respondent did not provide an answer to the exact income amount question. The closed-ended income range questions were constructed so that each successive question establishes a smaller range for the amount of the family’s income. For more information on the current income questions, see: 2011 NHIS public-use data release. NCHS. 2012. Available from: http://www.cdc.gov/nchs/nhis/2011imputedincome.htm.
    Also see: Pleis JR, Cohen RA. Impact of income bracketing on poverty measures used in the National Health Interview Survey’s Early Release Program: Preliminary data from the 2007 NHIS. Hyattsville, MD: NCHS. 2007. Available from: http://www.cdc.gov/nchs/data/nhis/income.pdf.
    Family income data are used in the computation of poverty level. Starting with Health, United States, 2004, a new methodology for imputing family income data for NHIS was implemented for data years 1997 and beyond. Multiple imputations were performed for survey years 1997 and beyond, with five sets of imputed values created to allow for the assessment of variability caused by imputation. A detailed description of the multiple imputation procedure, and data files for 1997 and beyond, are available from: http://www.cdc.gov/nchs/nhis/quest_data_related_1997_forward.htm, through the Data Release or the Imputed Income Files link under that year. For data years 1990–1996, about 16%–18% of persons had missing data for family income. In those years, missing values were imputed for family income by using a sequential hot deck within matrix cells imputation approach. A detailed description of the imputation procedure and data files, with imputed annual family income for 1990–1996, is available from: ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Datasets/NHIS/1990-96_Family_Income/. (Also see Appendix II, Table VI.)
  • National Health and Nutrition Examination Survey (NHANES)—In NHANES 1999 and onward, family income is asked in a series of questions about possible sources of income, including wages, salaries, interest and dividends, federal programs, child support, rents, royalties, and other possible sources. After the information about sources of income was obtained in the family interview income section of the questionnaire, the respondent was asked to report total combined family income for him- or herself and the other members of their family, in dollars. If the respondent did not provide an answer or did not know the total combined family income, he or she was asked if the total family income was less than $20,000 or $20,000 or more. If the respondent answered, a follow-up question asked the respondent to select an income range from a list on a printed flash card. The midpoint of the income range was then used as the total family income value. Family income values were used to calculate the poverty income ratio. NHANES II (1976–1980) included questions on components of income; NHANES III (1988–1994) did not ask the detailed components-of-income questions but asked respondents to identify their income based on a set of ranges provided on a flash card. Family income was not imputed for individuals or families with no reported income information in any of the NHANES survey years. (Also see Appendix II, Poverty.)
  • National Immunization Survey (NIS)—Prior to 1998, family income was the total income received by all family members in the past 12 months at the time of interview. Following the changes in the NHIS income questions, NIS changed the reference period for 1998 onward and collected income received by all family members for the calendar year prior to the interview year for households with age-eligible children (e.g., 2011 NIS family income data are based on calendar year 2010 income). Family income is the total income received by all members of a family before taxes. For the family income questions, the household respondent is asked to include income received from jobs, social security, retirement income, unemployment payments, public assistance, interest, dividends, net income from business, farm, rent, or any other sources. Respondents who answered “don’t know” or refused to give a dollar amount for the total family income were asked a cascading sequence of income questions (a total of 15 cascading questions that attempt to place the family income into one of 15 income intervals ranging from less than or equal to $7,500 to greater than or equal to $75,000). The initial question asks if the family income for the prior year was more or less than $20,000. Subsequent sets of income range questions are asked so that each successive question establishes a smaller income range. The midpoint of the income range is used as the total family income value for respondents who answered “don’t know” or refused to give a dollar amount. A family income variable is constructed from the total family income question and the cascading income questions. If an exact income is given, family income is set to this amount; otherwise it is set to the midpoint of the tightest bounds established by the cascading income questions. The values of the total family income are used to calculate an income-to-poverty ratio, which gives data users the flexibility to define any desired poverty level (e.g., 100% of poverty, 125% of poverty, or 200% of poverty). A household at or below the poverty level would have an income-to-poverty ratio less than or equal to 1.0. For NIS, this ratio is calculated only for households with age-eligible children, using the actual family income value or the midpoint of the interval from the series of cascading questions in the numerator and the poverty threshold provided by the Census Bureau for the size of the family and the number of related children in the household in the denominator. Details of the income questions and computation of the income-to-poverty ratio for each data collection year can be found in the NIS data documentation (Data User’s Guide and Household Interview Questionnaire) provided on the NIS website at: http://www.cdc.gov/nchs/nis/datasets.htm.
    For more information, see: Battaglia MP, Hoaglin DC, Izrael D, Khare M, Mokdad A. Improving income imputation by using partial income information and ecological variables. Presented at the American Statistical Association–Joint Statistical Meeting; 2002 Aug 11–15, New York, NY. Available from: http://www.cdc.gov/nchs/data/nis/estimation_weighting/Battaglia2002.pdf.
  • National Survey of Children’s Health (NSCH)—income included money from jobs, child support, Social Security, retirement income, unemployment payments, public assistance, interest, dividends, net income from business, farm, rent, and any other money income received. When a respondent did not supply a specific dollar amount for family income, they were asked a series of questions about whether the income was below, exactly at, or above threshold amounts. The unfolding bracket questions asked a series of closed-ended income range questions (e.g., “Is it less than $50,000?”). The closed-ended income range questions were constructed so that each successive question establishes a smaller range for the amount of the family’s income. If the respondent did not complete the series of unfolding bracket questions, either because they refused or did not know the answer to one of the questions, his or her income was set as “missing.” For the 2007 NSCH, income is missing for 8.5% of households. For the 2003 NSCH, income is missing for 9.0% of households. Missing income and household size were each imputed five times, to allow for the assessment of variability caused by imputation.
    For more information, see: Blumberg SJ, Foster EB, Frasier AM, et al. Design and operation of the National Survey of Children’s Health, 2007. NCHS. Vital Health Stat 2012;1(55). Available from: http://www.cdc.gov/nchs/data/series/sr_01/sr01_055.pdf.
    Also see: Imputed data in SLAITS microdata sets. Available from: http://www.cdc.gov/nchs/slaits/imputed_data.htm.

Federal hospital

See Appendix II, Hospital.

Fee-for-service health insurance

Fee-for-service health insurance is private (commercial) health insurance that reimburses health care providers on the basis of a fee for each health service provided to the insured person. It is also known as indemnity health insurance. In addition, “fee-for-service” is a term often applied to original Medicare, before Medicare managed-care plans or other new payment systems were introduced. (Also see Appendix II, Health insurance coverage; Managed care; Medicare.)

G

General hospital

See Appendix II, Hospital.

Geographic region

The U.S. Census Bureau groups the 50 states and the District of Columbia, for statistical purposes, into four geographic regions (Northeast, Midwest, South, and West) and nine divisions based on geographic proximity. (See Figure I.)

Figure I is a map of the United States showing U.S. Census Bureau geographic regions and divisions.

Figure IU.S. Census Bureau: Four geographic regions and nine divisions of the United States

Gestation

For the National Vital Statistics System and CDC’s Abortion Surveillance System, the period of gestation is defined as beginning with the first day of the last normal menstrual period and ending with the day of birth or day of termination of pregnancy. Data on gestational age are subject to error for several reasons, including imperfect maternal recall or misidentification of the last menstrual period because of postconception bleeding, delayed ovulation, or intervening early miscarriage.

Gross domestic product (GDP)

The GDP is the market value of the goods and services produced by labor and property located in the United States. As long as the labor and property are located in the United States, the suppliers (i.e., the workers and, for property, the owners) may be U.S. residents or residents of other countries. [Also see Appendix II, Consumer Price Index (CPI); Health expenditures, national.]

H

Health care contact

Starting in 1997, the National Health Interview Survey has collected information on health care contacts with doctors and other health care professionals by using the following questions: “During the past 12 months, how many times have you gone to a hospital emergency room about your own health?”, “During the past 12 months, did you receive care at home from a nurse or other health care professional? What was the total number of home visits received?”, and “During the past 12 months, how many times have you seen a doctor or other health care professional about your own health at a doctor’s office, a clinic, or some other place? Do not include times you were hospitalized overnight, visits to hospital emergency rooms, home visits, or telephone calls.” Starting with 2000 data, this question was amended to specifically exclude dental visits.

For 1997–1999, for each question, respondents were shown a flash card with response categories of 0, 1, 2–3, 4–9, 10–12, or 13 or more visits. For tabulation of the 1997–1999 data, responses of 2–3 were recoded to 2, responses of 4–9 were recoded to 6, responses of 10–12 were recoded to 11, and 13 or more visits were recoded to 13. The recoded values for the three types of visits were then added to yield an estimate of total health care contacts. Starting with 2000 data, response categories were expanded to 0, 1, 2–3, 4–5, 6–7, 8–9, 10–12, 13–15, or 16 or more. For 2000 and more recent data, these response categories were recoded to the midpoint of the range. The category of 16 or more was recoded to 16. The recoded values for the three types of visits were then added to yield an estimate of the summary measure of health care contacts (including doctor’s visits, hospital emergency room visits, and home visits). After summing the three component visit variables, respondents with values on the edge of the categories presented in Health, United States were rounded down to provide a more conservative estimate of the number of visits. For example, a respondent with 3.5 health care contacts was included in the 1–3 visits category, and a respondent with 9.5 health care contacts was included in the 4–9 visits category. Respondents were included in this analysis only if they were known on all three visit variables.

Analyses of the percentage of children without a health care visit are based on the following question: “During the past 12 months, how many times has [person] seen a doctor or other health care professional about (his/her) health at a doctor’s office, a clinic, or some other place? Do not include times [person] was hospitalized overnight, visits to hospital emergency rooms, home visits, or telephone calls.” (Also see Appendix II, Emergency department or emergency room visit; Home visit.)

Health expenditures, national

National health expenditures are estimated by the Centers for Medicare & Medicaid Services (CMS) and measure spending for health care in the United States by type of service delivered (e.g., hospital care, physician services, nursing home care) and source of funding for those services (e.g., private health insurance, Medicare, Medicaid, out-of-pocket spending). CMS produces both historical and projected estimates of health expenditures by category. [Also see Appendix II, Consumer Price Index (CPI); Gross domestic product (GDP).] Types of national health expenditures include:

  • National health expenditures estimates the amount spent for all health services and supplies, and health-related investment, produced in the United States during the calendar year. Detailed estimates are available by source of expenditure and by type of expenditure and are in current dollars for the year of report. Data are compiled from a variety of sources.
  • Health consumption expenditures are outlays for goods and services relating directly to patient care, plus expenses for administering health insurance programs and public health activities. This category is equivalent to total national health expenditures minus expenditures for investment in noncommercial research and structures and equipment.
  • Personal health care expenditures are outlays for goods and services relating directly to patient care. These expenditures are total national health expenditures minus expenditures for investment, health insurance program administration and the net cost of insurance, and public health activities.
  • Business, household, and other private expenditures are outlays for services provided or paid for by nongovernmental sources, such as consumers, private industry, and philanthropic and other non-patient-care sources.
  • Government expenditures are outlays for services provided or paid for by federal, state, and local government agencies or expenditures required by governmental mandate (such as workers’ compensation insurance payments).

Health insurance coverage

Health insurance is broadly defined to include both public and private payers who cover medical expenditures incurred by a defined population in a variety of settings.

  • National Health Interview Survey (NHIS)—For point-in-time health insurance estimates, NHIS respondents were asked about their coverage at the time of interview. For 1993–1996, respondents were asked about their coverage in the previous month. Questions on health insurance coverage were expanded starting in 1993, compared with previous years. In 1997, the entire questionnaire was redesigned and data were collected using a computer-assisted personal interview (CAPI). In 2007, questions on health insurance coverage were expanded again to include three new questions on high-deductible health plans, health savings accounts, and flexible spending accounts.
    Respondents were considered to be covered by private health insurance if they indicated private health insurance or, prior to 1997, if they were covered by a single-service hospital plan. Private health insurance includes managed care such as health maintenance organizations (HMOs).
    Private insurance obtained through the workplace was defined as any private insurance that was originally obtained through a present or former employer or union, or, starting in 1997, through the workplace, self-employment, or a professional association. Starting in 2011, respondents were also asked whether health insurance coverage was obtained through parents or another relative. Coverage obtained through parents or another relative was not included as workplace coverage.
    Until 1996, persons were defined as having Medicaid or other public assistance coverage if they indicated that they had either Medicaid or other public assistance or if they reported receiving Aid to Families with Dependent Children (AFDC) or Supplemental Security Income (SSI). After welfare reform in late 1996, Medicaid was delinked from AFDC and SSI. Starting in 1997, persons were considered to be covered by Medicaid if they reported Medicaid or a state-sponsored health program. Starting in 1999, persons were considered covered by Medicaid if they reported coverage by the Children’s Health Insurance Program (CHIP). Medicare or military health plan coverage was also determined in the interview, and starting in 1997 other government-sponsored program coverage was determined as well.
    If respondents did not report coverage under one of the above types of plans and they had unknown coverage under either private health insurance or Medicaid, they were considered to have unknown coverage.
    The remaining respondents without any indicated coverage were considered uninsured. The uninsured were persons who did not have coverage under private health insurance, Medicare, Medicaid, public assistance, a state-sponsored health plan, other government-sponsored programs, or a military health plan. Persons with only Indian Health Service coverage were considered uninsured. Estimates of the percentage of persons who were uninsured based on NHIS may differ slightly from those based on the March Current Population Survey (CPS) because of differences in survey questions, recall period, and other aspects of survey methodology.
    In NHIS, on average less than 2% of people aged 65 and over reported no current health insurance coverage, but the small sample size precludes the presentation of separate estimates for this population. Therefore, the term “uninsured” refers only to the population under age 65.
    Two additional questions were added to the health insurance section of NHIS beginning with the third quarter of 2004 (Table VII). One question was asked of persons aged 65 and over who had not indicated that they had Medicare: “People covered by Medicare have a card which looks like this. [Are/Is] [person] covered by Medicare?” The other question was asked of persons under age 65 who had not indicated any type of coverage: “There is a program called Medicaid that pays for health care for persons in need. In this state it is also called [state name]. [Are/Is] [person] covered by Medicaid?” Respondents who originally classified themselves as uninsured, but whose classification was changed to Medicare or Medicaid on the basis of a “yes” response to either question, subsequently received appropriate follow-up questions concerning periods of noncoverage for insured respondents. Of the 892 people (unweighted) who were eligible to receive the Medicare probe question in the third and fourth quarters of 2004, 55% indicated that they were covered by Medicare. Of the 9,146 people (unweighted) who were eligible to receive the Medicaid probe question in the third and fourth quarters of 2004, 3% indicated that they were covered by Medicaid. Estimates in Health, United States were calculated using the responses to the two additional probe questions. For a complete discussion of the effect of the addition of these two probe questions on the estimates for insurance coverage, see: Cohen RA, Martinez ME. Impact of Medicare and Medicaid probe questions on health insurance estimates from the National Health Interview Survey, 2004. Health E-Stats. NCHS; 2005. Available from: http://www.cdc.gov/nchs/data/hestat/impact04/impact04.htm.
    Survey respondents may be covered by health insurance at the time of interview but may have experienced one or more lapses in coverage during the 12 months prior to interview. Starting with Health, United States, 2006, NHIS estimates have been presented for the following three exhaustive categories: (a) people with health insurance continuously for the full 12 months prior to interview, (b) those who had a period of up to 12 months prior to interview without coverage, and (c) those who were uninsured for more than 12 months prior to interview. This stub variable has been added to selected tables. Two additional NHIS questions were used to determine the appropriate category for the survey respondents: (a) all persons without a known comprehensive health insurance plan were asked, “About how long has it been since [person] last had health care coverage?”; and (b) all persons with known health insurance coverage were asked, “In the past 12 months, was there any time when [person] did NOT have ANY health insurance coverage?”

[Also see Appendix II, Children’s Health Insurance Program (CHIP); Fee-for-service health insurance; Health maintenance organization (HMO); Managed care; Medicaid; Medicare; Uninsured.]

Health maintenance organization (HMO)

An HMO is a health care system that assumes or shares both the financial risks and the delivery risks associated with providing comprehensive medical services to a voluntarily enrolled population in a particular geographic area, usually in return for a fixed, prepaid fee. Pure HMO enrollees use only the prepaid, capitated health services of the HMO panel of medical care providers. Open-ended HMO enrollees use the prepaid HMO health services but may also receive medical care from providers who are not part of the HMO panel. There is usually a substantial deductible, copayment, or coinsurance associated with use of nonpanel providers. HMO model types are as follows:

  • Group model HMO is an HMO that contracts with a single multispecialty medical group to provide care to the HMO’s membership. The group practice may work exclusively with the HMO, or it may provide services to non-HMO patients as well. The HMO pays the medical group a negotiated per capita rate, which the group distributes among its physicians, usually on a salaried basis.
  • Staff model HMO is a closed-panel HMO (where patients can receive services only through a limited number of providers) in which physicians are HMO employees. The providers see members in the HMO’s own facilities.
  • Network model HMO is an HMO that contracts with multiple physician groups to provide services to HMO members. It may include single or multispecialty groups.
  • Individual practice association (IPA) is a health care provider organization composed of a group of independent practicing physicians who maintain their own offices and band together for the purpose of contracting their services to HMOs, preferred provider organizations, and insurance companies. An IPA may contract with and provide services to both HMO and non-HMO plan participants.
  • Mixed model HMO is an HMO that combines features of more than one HMO model.

[Also see Appendix II, Managed care; Preferred provider organization (PPO).]

Health services and supplies expenditures

See Appendix II, Health expenditures, national.

Health status, respondent-assessed

Health status was measured in the National Health Interview Survey by asking the family respondent about his or her health or the health of a family member: “Would you say [person’s] health in general is excellent, very good, good, fair, or poor?”

Hearing trouble

In the National Health Interview Survey, information about hearing trouble is obtained by asking respondents how well they hear without the use of hearing aids. Prior to 2007 data, respondents were asked, “Which statement best describes your hearing without a hearing aid: good, a little trouble, a lot of trouble, or deaf?” In Health, United States, a lot of trouble and deaf are combined into one category: hearing trouble. Starting with 2007 data, the question was revised to expand the response categories. Respondents were asked, “These next questions are about your hearing WITHOUT the use of hearing aids or other listening devices. Is your hearing excellent, good, a little trouble hearing, moderate trouble, a lot of trouble, or are you deaf?” For 2007 and subsequent data, a lot of trouble and deaf are still combined into the one category, hearing trouble, in Health, United States. However, because of the expanded response categories, 2007 and subsequent data are not strictly comparable with earlier years and caution is urged when interpreting trends. For example, in 2006, 3.5% of adults (aged 18 and over) were classified as having hearing difficulty (response categories: a lot of trouble or deaf ). In 2007, 2.3% of adults (aged 18 and over) were classified as having hearing difficulty (response categories: a lot of trouble or deaf ). This more than 30% decline from 2006 to 2007 in the estimate of those with hearing trouble is likely attributable to the addition of the moderate trouble response category, rather than changes in the prevalence of hearing trouble. Although all age groups saw a decline in the percentage reporting hearing trouble between 2006 and 2007, the amount of the decline varied. There was a 50% decline in reported hearing trouble among adults aged 18–44 (from 0.8% in 2006 to 0.4% in 2007). Among adults aged 45–64, the percentage that reported hearing trouble declined 43%, from 3.5% in 2006 to 2.0% in 2007. Among adults aged 65 and over, reported hearing trouble declined 24%, from 11.4% in 2006 to 8.7% in 2007. For all age groups, these declines are likely attributable to the additional response categories in the revised hearing question.

For more information, see: Pleis JR, Lucas JW. Summary health statistics for U.S. adults: National Health Interview Survey, 2007. NCHS. Vital Health Stat 2009;10(240). Available from: http://www.cdc.gov/nchs/data/series/sr_10/sr10_240.pdf.

Hispanic origin

Hispanic or Latino origin includes persons of Mexican, Puerto Rican, Cuban, Central and South American, and other or unknown Latin American or Spanish origin. Persons of Hispanic origin may be of any race.

  • Birth file—The reporting area for an Hispanic-origin item on the birth certificate expanded between 1980 and 1993 [when the Hispanic item was included on the birth certificate in all states and the District of Columbia (D.C.)]. Trend data on births of Hispanic and non-Hispanic parentage in Health, United States are affected by expansion of the reporting area and by immigration. These two factors affect numbers of events, composition of the Hispanic population, and maternal and infant health characteristics.
    In 1980 and 1981, information on births of Hispanic parentage was reported on the birth certificate by the following 22 states: Arizona, Arkansas, California, Colorado, Florida, Georgia, Hawaii, Illinois, Indiana, Kansas, Maine, Mississippi, Nebraska, Nevada, New Jersey, New Mexico, New York, North Dakota, Ohio, Texas, Utah, and Wyoming. In 1982 Tennessee, and in 1983 D.C., began reporting this information. Between 1983 and 1987, information on births of Hispanic parentage was available for 23 states and D.C. In 1988, this information became available for Alabama, Connecticut, Kentucky, Massachusetts, Montana, North Carolina, and Washington state, increasing the number of states reporting information on births of Hispanic parentage to 30 states and D.C. In 1989, this information became available from an additional 17 states, increasing the number of Hispanic-reporting states to 47 and D.C. In 1989, only Louisiana, New Hampshire, and Oklahoma did not report Hispanic parentage on the birth certificate. With the inclusion of Louisiana in 1989 and Oklahoma in 1990 as Hispanic-reporting states, 99% of birth records included information on mother’s origin. Hispanic origin of the mother was reported on the birth certificates of 49 states and D.C. in 1991 and 1992; only New Hampshire did not provide this information. Starting in 1993, Hispanic origin of mother was reported by all 50 states and D.C.
    Starting with 2003 data, some states began using the 2003 revision of the U.S. Standard Certificate of Live Birth. Hispanic origin and race are collected separately on the birth certificate. The Hispanic origin question on the 2003 revision of the birth certificate asks respondents to select only one response. Occasionally, more than one Hispanic origin response is given (0.1% of births in 2010). When this occurs, all responses are collected, and these respondents are classified as “other Hispanic.”
  • Mortality file—The reporting area for an Hispanic-origin item on the death certificate expanded between 1985 and 1997. In 1985, mortality data by Hispanic origin of decedent were based on deaths of residents of the following 17 states and D.C. whose data on the death certificate were at least 90% complete on a place-of-occurrence basis and of comparable format: Arizona, Arkansas, California, Colorado, Georgia, Hawaii, Illinois, Indiana, Kansas, Mississippi, Nebraska, New York, North Dakota, Ohio, Texas, Utah, and Wyoming. In 1986, New Jersey began reporting Hispanic origin of decedent, increasing the number of reporting states to 18 and D.C. in 1986 and 1987. In 1988, Alabama, Kentucky, Maine, Montana, North Carolina, Oregon, Rhode Island, and Washington state were added to the reporting area, increasing the number of states to 26 and D.C. In 1989, an additional 18 states were added, increasing the Hispanic reporting area to 44 states and D.C.; only Connecticut, Louisiana, Maryland, New Hampshire, Oklahoma, and Virginia were not included in the reporting area. Starting with 1990 data in Health, United States, the criterion was changed to include states whose data were at least 80% complete. In 1990, Maryland, Virginia, and Connecticut; in 1991 Louisiana; and in 1993 New Hampshire were added, increasing the reporting area for Hispanic origin of decedent to 47 states and D.C. in 1990; 48 states and D.C. in 1991 and 1992; and 49 states and D.C. in 1993–1996. Only Oklahoma did not provide this information in 1993–1996. Starting in 1997, Hispanic origin of decedent was reported by all 50 states and D.C. Based on data from the U.S. Census Bureau, the 1990 reporting area encompassed 99.6% of the U.S. Hispanic population. In 1990, more than 96% of death records included information on Hispanic origin of the decedent.
    Starting with 2003 data, some states began using the 2003 revision of the U.S. Standard Certificate of Death, which allows the reporting of more than one race (multiple races) and includes some revisions in the item reporting Hispanic origin. In 2010, 34 states and D.C. reported multiple-race data. The effect of the 2003 revision of the Hispanic origin item on the reporting of Hispanic origin on death certificates is presumed to be minor. For more information, see Appendix II, Race. Also see the Technical Notes section of the annual series of “Deaths: Final Data” reports, available from: http://www.cdc.gov/nchs/products/nvsr.htm; and NCHS procedures for multiple-race and Hispanic origin data: Collection, coding, editing, and transmitting. Hyattsville, MD: NCHS; 2004. Available from: http://www.cdc.gov/nchs/data/dvs/Multiple_race_docu_5-10-04.pdf.
  • National Health Interview Survey (NHIS) and National Health and Nutrition Examination Survey (NHANES)—Questions on Hispanic origin are self-reported in NHANES III and subsequent years, and since 1976 in NHIS, and precede questions on race. For 1999–2006 data, the NHANES sample was designed to provide estimates specifically for persons of Mexican origin and not for all Hispanic-origin persons in the United States. Persons of Hispanic origin other than Mexican were entered into the sample with different selection probabilities that are not nationally representative of the total U.S. Hispanic population. Starting with 2007–2008 data collection, all Hispanic persons were oversampled, not just Mexican-American persons. For more information on the sampling methodology changes, see http://www.cdc.gov/nchs/nhanes/nhanes2007-2008/sampling_0708.htm. For more information on race and Hispanic origin in NHIS, see the NHIS Race and Hispanic Origin Information home page. Available from: http://www.cdc.gov/nchs/nhis/rhoi.htm.
  • Surveillance, Epidemiology, and End Results (SEER) Program—SEER data are available from the National Institutes of Health, National Cancer Institute. SEER Hispanic data used inHealth, United States tables exclude data from Alaska. The North American Association of Central Cancer Registries, Inc. (NAACCR) Hispanic Identification Algorithm was used on a combination of variables to classify incidence cases as Hispanic for analytic purposes. See: NAACCR guideline for enhancing Hispanic–Latino identification. Bethesda, MD: National Cancer Institute; 2003. Available from: http://seer.cancer.gov/seerstat/variables/seer/yr1973_2004/race_ethnicity/.
  • Youth Risk Behavior Survey (YRBS)—Prior to 1999, a single question was asked about race and Hispanic origin, with the option of selecting one of the following categories: white not Hispanic, black not Hispanic, Hispanic or Latino, Asian or Other Pacific Islander, American Indian or Alaska Native, or other. Between 1999 and 2003, respondents were asked a single question about race and Hispanic origin with the option of choosing one or more of the following categories: white, black or African American, Hispanic or Latino, Asian, Native Hawaiian or Other Pacific Islander, or American Indian or Alaska Native. Beginning in 2005, respondents were asked a question about Hispanic origin (“Are you Hispanic or Latino?”) and a second separate question about race that included the option of selecting one or more of the following categories: American Indian or Alaska Native, Asian, black or African American, Native Hawaiian or Other Pacific Islander, or white. Because of the differences between questions, the data about race and Hispanic ethnicity for the years prior to 1999 are not strictly comparable with estimates for the subsequent years. However, analyses of data collected between 1991 and 2003 have indicated that the data are comparable across years and can be used to study trends. See Appendix II, Race; and see: Brener ND, Kann L, McManus T. A comparison of two survey questions on race and ethnicity among high school students. Public Opin Q 2003;67(2):227–36.

Home visit

Starting in 1997, the National Health Interview Survey has been collecting information on home visits received during the 12 months prior to interview. Respondents are asked, “During the past 12 months, did you receive care at home from a nurse or other health care professional? What was the total number of home visits received?” These data are combined with data on visits to doctors’ offices, clinics, and emergency departments to provide a summary measure of health care visits. (Also see Appendix II, Emergency department or emergency room visit; Health care contact.)

Hospital

According to the American Hospital Association (AHA), hospitals are licensed institutions with at least six beds whose primary function is to provide diagnostic and therapeutic patient services for medical conditions; they have an organized physician staff and provide continuous nursing services under the supervision of registered nurses. The World Health Organization (WHO) considers an establishment to be a hospital if it is permanently staffed by at least one physician, can offer inpatient accommodation, and can provide active medical and nursing care. Hospitals may be classified by type of service, ownership, size in terms of number of beds, and length of stay. In the National Hospital Ambulatory Medical Care Survey, hospitals include all those with an average length of stay for all patients of less than 30 days (short-stay) or hospitals whose specialty is general (medical or surgical) or children’s general. Federal hospitals and hospital units of institutions and hospitals with fewer than six beds staffed for patient use are excluded. (Also see Appendix II, Average length of stay; Bed, health facility; Days of care; Emergency department; Inpatient; Outpatient department.)

  • Community hospital—Community hospitals, based on the AHA definition, include all nonfederal, short-term general and special hospitals whose facilities and services are available to the public. Special hospitals include obstetrics and gynecology; eye, ear, nose, and throat; rehabilitation; orthopedic; and other specialty services. Short-term general and special children’s hospitals are also considered to be community hospitals. A hospital may include a nursing-home-type unit and still be classified as short-term, provided the majority of its patients are admitted to units where the average length of stay is less than 30 days. Hospital units of institutions such as prisons and college infirmaries that are not open to the public and are contained within a nonhospital facility are not included in the category of community hospitals. Traditionally, the definition included all nonfederal short-stay hospitals except facilities for the mentally retarded. In a revised definition, the following additional sites were excluded: hospital units of institutions, and alcoholism and chemical dependency facilities.
  • Federal hospital—Federal hospitals are those operated by the federal government.
  • For-profit hospital—For-profit hospitals are operated for profit by individuals, partnerships, or corporations.
  • General hospital—General hospitals provide diagnostic, treatment, and surgical services for patients with a variety of medical conditions. According to WHO, these hospitals provide medical and nursing care for more than one category of medical discipline (e.g., general medicine, specialized medicine, general surgery, specialized surgery, and obstetrics). Excluded are hospitals, usually in rural areas, that provide a more limited range of care.
  • Nonprofit hospital—Nonprofit hospitals are those controlled by nonprofit organizations, such as religious organizations and fraternal societies.
  • Registered hospital—Registered hospitals are those registered with AHA. About 98% of U.S. hospitals are registered.
  • Short-stay hospital—In the National Hospital Discharge Survey, short-stay hospitals are those in which the average length of stay is less than 30 days. The National Health Interview Survey defines short-stay hospitals as any hospital or hospital department in which the type of service provided is general; maternity; eye, ear, nose, and throat; children’s; or osteopathic.
  • Special hospital—Special hospitals are those, such as psychiatric, tuberculosis, chronic disease, rehabilitation, maternity, and alcoholic or narcotic dependency facilities, that provide a particular type of service to the majority of their patients.

Hospital-based physician

See Appendix II, Physician.

Hospital day

See Appendix II, Days of care.

Hospital utilization

Estimates of hospital utilization (such as hospital discharge rate, days of care rate, average length of stay, and percentage of the population with a hospitalization) presented in Health, United States are based on data from four sources: the Healthcare Cost and Utilization Project, Nationwide Inpatient Sample (HCUP– NIS); the National Health Interview Survey (NHIS); the National Hospital Discharge Survey (NHDS); and the American Hospital Association (AHA). HCUP–NIS data are based on hospital stays for persons discharged alive or deceased from about 1,000 hospitals sampled to approximate a 20% stratified sample of U.S. community hospitals. NHIS data are based on household interviews of the civilian noninstitutionalized population and thus exclude hospitalizations for institutionalized persons and those who died while hospitalized. NHDS data are based on hospital discharge records of persons who had an inpatient stay in a nonfederal, short-stay hospital. NHDS includes hospital discharge records for persons discharged alive or deceased and for institutionalized persons. The NHDS tables shown in Health, United States exclude data for newborns. Estimates for average length of stay between the NHDS and AHA data presented in Health, United States differ because of different methods for counting days of care. [Also see Appendix II, Average length of stay; Days of care; Discharge; and Appendix I, Healthcare Cost and Utilization Project (HCUP), Nationwide Inpatient Sample; National Health Interview Survey (NHIS); National Hospital Discharge Survey (NHDS).]

Human immunodeficiency virus (HIV) disease

HIV disease is caused by infection with a cytopathic retrovirus, which in turn leads to destruction of parts of the immune system. A surveillance case for HIV requires laboratory-confirmed evidence of infection, including a positive result on a screening test for HIV antibody, followed by a positive result on a confirmatory test, or a positive result or detectable quantity on an HIV virologic test [see MMWR 2008;57(RR–10):1–8].

Since 1985, many states and U.S. dependent areas have implemented HIV case reporting as part of their comprehensive HIV and AIDS surveillance programs. As of April 2008, all states, the District of Columbia, and five U.S. independent areas had implemented HIV case surveillance using a confidential system for name-based case reporting for both HIV infection and AIDS. To better capture and characterize populations in which HIV infection has been newly diagnosed, including persons with evidence of recent HIV infection, many states report the prevalence of those living with a diagnosis of HIV infection, including those living with AIDS. In 2008, changes were made to the case definition for HIV infection. The new case definition combined the two previous case definitions for HIV and AIDS and established a new disease staging classification. The term HIV/AIDS was replaced with the term “diagnosis of HIV infection” [see MMWR 2008;57(RR–10):1–8]. Mortality and morbidity coding for HIV disease are similar and have evolved over time.

  • Mortality coding—Starting with 1999 data and the introduction of the 10th revision of the International Classification of Diseases (ICD–10), the title for this cause of death was changed from HIV infection to HIV disease, and the ICD codes were changed to B20–B24. Starting with 1987 data, NCHS introduced category numbers *042–*044 for classifying and coding HIV infection as a cause of death in ICD–9. The asterisks before the category numbers indicate that these codes were not part of the original ICD–9. HIV infection was formerly referred to as human T-cell lymphotropic virus-III/lymphadenopathy-associated virus (HTLV–III/LAV) infection. Before 1987, deaths involving HIV infection were classified to Deficiency of cell-mediated immunity (ICD–9 code 279.1) contained in the title All other diseases; to Pneumocystosis (ICD–9 code 136.3) contained in the title All other infectious and parasitic diseases; to Malignant neoplasms, including neoplasms of lymphatic and hematopoietic tissues; and to a number of other causes. Therefore, before 1987, death statistics for HIV infection are not strictly comparable with data for 1987 and subsequent years and are not shown in Health, United States.
  • Morbidity coding—The National Hospital Discharge Survey codes diagnosis data using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD–9–CM). During 1984 and 1985, only data for AIDS (ICD–9–CM code 279.19) were included. In 1986–1994, discharges with the following diagnoses were included: AIDS, HIV infection and associated conditions, and positive serological or viral culture findings for HIV (ICD–9–CM codes 042–044, 279.19, and 795.8). Beginning in 1995, discharges with the following diagnoses were included: HIV disease and asymptomatic HIV infection status (ICD–9–CM codes 042 and V08).

[Also see Appendix II, Acquired immunodeficiency syndrome (AIDS); Cause of death; International Classification of Diseases (ICD); International Classification of Diseases, 9th Revision, Clinical Modification (ICD–9–CM); Tables IV and X.]

I

Illicit drug use

Illicit drug use refers to the use and misuse of illegal and controlled drugs.

  • Monitoring the Future (MTF) Study—In this school-based survey of secondary school students, information on illicit drug use is collected using self-completed questionnaires. The information is based on the following questions: “On how many occasions (if any) have you used marijuana in the last 30 days?” and “On how many occasions (if any) have you used hashish in the last 30 days?” Questions on cocaine use include the following: “On how many occasions (if any) have you taken crack (cocaine in chunk or rock form) during the last 30 days?” and “On how many occasions (if any) have you taken cocaine in any other form during the last 30 days?”
  • National Survey on Drug Use & Health (NSDUH)— Information on illicit drug use is collected for survey participants aged 12 and over. Information on any illicit drug use includes any use of marijuana or hashish, cocaine, heroin, hallucinogens, or inhalants, as well as nonmedical use of prescription psychotherapeutic drugs. Current use (within the past month) is based on the question: “How long has it been since you last used (drug name)?” (Also see Appendix II, Substance use.)

Immunization

See Appendix II, Vaccination.

Incidence

Incidence is the number of cases of disease having their onset during a prescribed period of time. It is often expressed as a rate (e.g., the incidence of measles per 1,000 children aged 5–15 during a specified year). Measuring incidence may be complicated because the population at risk for the disease may change during the period of interest, for example, due to births, deaths, or migration. In addition, determining whether a case is new—that is, whether its onset occurred during the prescribed period of time—may be difficult. Because of these difficulties in measuring incidence, many health statistics are instead measured in terms of prevalence. (Also see Appendix II, Prevalence.)

Individual practice association (IPA)

See Appendix II, Health maintenance organization (HMO).

Industry of employment

For the presentation of data in Health, United States, industries are classified according to the North American Industry Classification System (NAICS). For each year of data presented, the most recent version of NAICS was used. NAICS groups establishments into industries based on their production or supply function: establishments using similar raw material inputs, capital equipment, and labor are classified in the same industry. This approach creates homogeneous categories well suited for economic analysis. NAICS uses a six-digit hierarchical coding system to classify all economic activity into 20 industry sectors. The first two digits of the six-digit code designate the highest level of aggregation, into the government and 19 private industry sectors (Table VIII). With the exception of the agriculture, forestry, farming, and hunting sector, private industry sectors are classified as goods- or service-producing. Mining, construction, and manufacturing are primarily goods-producing sectors, and the remaining 15 are entirely service-providing sectors. NAICS allows for the classification of 1,170 industries. For more information on NAICS, see: http://www.census.gov/eos/www/naics.

NAICS replaces the Standard Industrial Classification (SIC) system, originally designed in the 1930s and revised and updated periodically to reflect changes in the U.S. economy. The last SIC revision was in 1987. The SIC system focused on the manufacturing sector of the economy and provided significantly less detail for the now-dominant service sector, including newly developed industries in information services, health care delivery, and high-tech manufacturing. Although some titles in SIC and NAICS are similar, there is little comparability between the two systems because industry groupings are defined differently. Estimates of deaths, injuries, and illnesses classified by NAICS should not be compared with earlier estimates that used SIC.

Starting with Health United States, 2005, health data by industry from the Bureau of Labor Statistics’ Census of Fatal Occupational Injuries (CFOI) and Survey of Occupational Injuries and Illnesses (SOII) data systems are classified using the NAICS system and replace trends in occupational health data based on the SIC system in previous editions of Health, United States.

Infant death

An infant death is the death of a live-born child before his or her first birthday. Age at death may be further classified as neonatal or postneonatal. Neonatal deaths are those that occur before the 28th day of life; postneonatal deaths are those that occur within 28 days to under 1 year of age. (Also see Appendix II, Rate: Death and related rates.)

Injury

The International Classification of External Causes of Injuries (ICECI) Coordination and Maintenance Group defines injury as a (suspected) bodily lesion resulting from acute overexposure to energy (this can be mechanical, thermal, electrical, chemical, or radiant) interacting with the body in amounts or rates that exceed the threshold of physiological tolerance. The time between exposure to the energy and the appearance of an injury is short. In some cases, an injury results from an insufficiency of any of the vital elements (i.e., air, water, or warmth), as in strangulation, drowning, or freezing. Acute poisonings and toxic effects, including overdoses of substances and wrong substances given or taken in error are included, as are adverse effects and complications of therapeutic, surgical, and medical care. Psychological harm is excluded. Injuries can be intentional or unintentional (i.e., accidental). In NCHS data systems, external causes of nonfatal injuries are coded to the International Classification of Diseases, 9th Revision, Clinical Modification, Supplementary Classification of External Causes of Injury and Poisoning, and the codes are often referred to as E codes. See Table IX for a list of external causes of injury categories and E codes used in Health, United States. Also see the NCHS injury website at: http://www.cdc.gov/nchs/injury.htm; and see: ICECI Coordination and Maintenance Group. International Classification of External Causes of Injuries (ICECI), ver 1.2. Amsterdam, The Netherlands: Consumer Safety Institute; and Adelaide, Australia: Australian Institute of Health and Welfare National Injury Surveillance Unit. Flinders University; 2004. Available from: http://www.who.int/classifications/icd/adaptations/iceci/en/index.html. (Also see Appendix II, Diagnosis; Injury-related visit.)

Injury-related visit

In the National Hospital Ambulatory Medical Care Survey (NHAMCS), an emergency department visit was considered injury-related if the physician diagnosis was injury-related or an external cause-of-injury code (E code) was present (Tables IX and X). Starting with Health, United States, 2008, an injury-related visit was redefined as an initial injury visit. In the 2001–2010 NHAMCS, an initial injury visit was the first visit to an emergency department for an injury that was characterized by either the first-listed diagnosis being a valid injury diagnosis or by a valid first-listed E code, regardless of the diagnosis code. Visits for which the first-listed diagnosis or the first-listed E code was for a complication of medical care or for an adverse event were not counted as injury visits. For 2001–2004 and 2007–2010 data, the patient record form had a specific question on whether the episode of care was an initial visit for the problem. In the 2005 and 2006 surveys, this variable was not included, and in its place an imputed variable was constructed that indicated whether the visit was or was not the initial visit for the problem. For an explanation of the methodology used to create the imputed initial visit variable, see: http://www.cdc.gov/nchs/data/ahcd/initialvisit.pdf. For more information, see the CDC/NCHS Injury Data and resources website at: http://www.cdc.gov/nchs/injury.htm; and Fingerhut LA. Recommended definition of initial injury visits to emergency departments for use with the NHAMCS–ED data. NCHS. Health E-Stats; 2006. Available from: http://www.cdc.gov/nchs/data/hestat/injury/injury.htm. (Also see Appendix II, Emergency department or emergency room visit; External cause of injury; Injury.)

Inpatient

An inpatient is a person who is formally admitted to the inpatient service of a hospital for observation, care, diagnosis, or treatment. (Also see Appendix II, Admission; Average length of stay; Days of care; Discharge; Hospital.)

Inpatient day

See Appendix II, Days of care.

Instrumental activities of daily living (IADL)

IADLs are activities related to independent living and include preparing meals, managing money, shopping for groceries or personal items, performing light or heavy housework, and using a telephone. In the National Health Interview Survey, respondents are asked whether they or family members aged 18 and over need the help of another person for handling routine IADL needs because of a physical, mental, or emotional problem.

In the Medicare Current Beneficiary Survey, if a sample person had any difficulty performing an activity by him- or herself and without special equipment, or did not perform the activity at all because of health problems, the person was categorized as having a limitation in that activity. The limitation may have been temporary or chronic at the time of interview. Sample persons in the community answered health status and functioning questions themselves, if able to do so. For sample persons in a long-term care facility, a proxy such as a nurse answered questions about the sample person’s health status and functioning. [Also see Appendix II, Activities of daily living (ADL); Complex activity limitation; Limitation of activity.]

Intermediate care facility

See Appendix II, Nursing home.

International Classification of Diseases (ICD)

The ICD is used to code and classify cause-of-death data. The ICD is developed collaboratively by the World Health Organization and 10 international centers, one of which is housed at NCHS. The purpose of the ICD is to promote international comparability in the collection, classification, processing, and presentation of health statistics. Since 1900, the ICD has been modified about once every 10 years, except for the 20-year interval between the 9th and 10th revisions (ICD–9 and ICD–10) (Table III). The purpose of the revisions is to stay abreast of advances in medical science. New revisions usually introduce major disruptions in time series of mortality statistics (Tables IV and V). For more information, see the NCHS ICD–10 website at: http://www.cdc.gov/nchs/icd/icd10.htm. [Also see Appendix II, Cause of death; Comparability ratio; International Classification of Diseases, 9th Revision, Clinical Modification (ICD–9–CM).]

International Classification of Diseases, 9th Revision, Clinical Modification (ICD–9–CM)

ICD–9–CM is based on, and is compatible with, the World Health Organization’s ICD–9. The United States currently uses ICD–9–CM to code morbidity diagnoses and inpatient procedures. ICD–9–CM consists of three volumes. Volumes 1 and 2 contain the diagnosis tabular list and index; Volume 3 contains the procedure classification (tabular list and index combined). ICD–9–CM is divided into 17 chapters and two supplemental classifications. The chapters are arranged primarily by body system. In addition, there are chapters for Infectious and parasitic diseases; Neoplasms; Endocrine, nutritional, and metabolic diseases; Mental disorders; Complications of pregnancy, childbirth, and puerperium; Certain conditions originating in the perinatal period; Congenital anomalies; and Symptoms, signs, and ill-defined conditions. The two supplemental classifications are for factors influencing health status and contact with health services (V codes), and for external causes of injury and poisoning (E codes).

In Health, United States, morbidity data are classified using ICD–9–CM. Diagnostic categories and codes for ICD–9–CM are shown in Table X; ICD–9–CM procedure categories and codes are shown in Tables XI and XII. For more information about ICD–9–CM, see the NCHS Classification of Diseases, Functioning, and Disability website at: http://www.cdc.gov/nchs/icd.htm. [Also see Appendix II, International Classification of Diseases (ICD).]

L

Leading causes of death

See Appendix II, Cause-of-death ranking.

Life expectancy

Life expectancy is the average number of years of life remaining to a person at a particular age and is based on a given set of age-specific death rates—generally the mortality conditions existing in the period mentioned. Life expectancy may be determined by sex, race and Hispanic origin, or other characteristics by using age-specific death rates for the population with that characteristic. (Also see Appendix II, Rate: Death and related rates.)

U.S. life tables by Hispanic origin were available starting with 2006 data. Life expectancy data for the Hispanic population was not available before 2006 for three major reasons: (a) coverage of the Hispanic population in the U.S. mortality statistics system was incomplete, (b) misclassification of Hispanic persons on death certificate data underestimated deaths in the Hispanic population, and (c) misstatement of age at the oldest ages in the Hispanic population led to an underestimation of mortality at the oldest ages.

Hispanic origin was added to the U.S. standard death certificate in 1989, but it was not adopted by every state until 1997. By 1997, all states had reporting at rates over 99%. Research on race and Hispanic origin reporting on U.S. death certificates found that misclassification of race and Hispanic origin accounts for a net underestimate of 5% for total Hispanic deaths and 1% for total non-Hispanic black deaths, and a net overestimate of 0.5% for non-Hispanic white deaths. To address the effects of age misstatement at the oldest ages, the probability of death for Hispanic persons over age 80 is estimated as a function of non-Hispanic white mortality with the use of the Brass relational logit model. For more information, see: Arias E. United States life tables by Hispanic origin. NCHS. Vital Health Stat 2010;2(152). Available from: http://www.cdc.gov/nchs/data/series/sr_02/sr02_152.pdf.

In 2000, the life table methodology was revised. The revised methodology is similar to that developed for the 1999–2001 decennial life tables. In 2008, the life table methodology was refined in two important ways. First, a logistic rather than a nonlinear least squares model was used to smooth and extrapolate the Vital and Medicare blended death rates at the older ages. Second, the age at which smoothing is begun was raised from 66 to 85 years or so, depending on the population. Values for data years 2001–2010 are based on the latest revision. As a result, data post-2000 may differ from figures published previously. For a full description of the new life table methodology, see: Arias E. United States life tables, 2008. National vital statistics reports; vol 61 no 3. Hyattsville, MD: NCHS; 2012. Available from: http://www.cdc.gov/nchs/data/nvsr/nvsr61/nvsr61_03.pdf.

Limitation of activity

Limitation of activity may be defined in different ways, depending on the conceptual framework. In the National Health Interview Survey, limitation of activity refers to a long-term reduction in a person’s capacity to perform the usual kind or amount of activities associated with his or her age group as a result of a chronic condition. Limitation of activity is assessed by asking persons a series of questions about limitations in their or a family member’s ability to perform activities usual for their age group because of a physical, mental, or emotional problem. Persons are asked about limitations in activities of daily living, instrumental activities of daily living, play, school, work, difficulty walking or remembering, and any other activity limitations. For reported limitations, the causal health conditions are determined, and persons are considered limited if one or more of these conditions is chronic. Children under age 18 who receive special education or early intervention services are considered to have a limitation of activity. [Also see Appendix II, Activities of daily living (ADL); Instrumental activities of daily living (IADL).]

Long-term care facility

A long-term care facility is a residence that provides a specific level of personal or medical care or supervision to residents. In the Medicare Current Beneficiary Survey, a residence is considered a long-term care facility if it has three or more long-term care beds and answers affirmatively to at least one of three questions: “Does this facility (a) provide personal care services to residents, (b) provide continuous supervision of residents, (c) provide any long-term care?” Types of long-term care facilities include licensed nursing homes, skilled nursing homes, intermediate care facilities, retirement homes (that provide services), domiciliary or personal care facilities, distinct long-term care units in a hospital complex, mental health facilities and centers, assisted and foster care homes, and institutions for the mentally retarded and developmentally disabled. (Also see Appendix II, Nursing home.)

Low birthweight

See Appendix II, Birthweight.

M

Mammography

A mammogram is an x-ray image of the breast used to detect irregularities in breast tissue. In the National Health Interview Survey, questions concerning use of mammography were asked on an intermittent schedule, and question content differed across years. In 1987 and 1990, women were asked to report when they had their last mammogram. In 1991, women were asked whether they had a mammogram in the past 2 years. In 1993 and 1994, women were asked whether they had a mammogram within the past year, between 1 and 2 years ago, or over 2 years ago. In 1998, women were asked whether they had a mammogram a year ago or less, more than 1 year but not more than 2 years, or more than 2 years ago.

In 1999, women were asked when they had their most recent mammogram, in days, weeks, months, or years. Ten percent of women in the sample responded “2 years ago,” and in this analysis these women were coded as within the past 2 years, although a response of 2 years ago may include women whose last mammogram was more than 2 but less than 3 years ago. Thus, estimates for 1999 are overestimated to some degree in comparison with estimates in previous years.

In 2000 and 2003, women were asked when they had their most recent mammogram (give month and year). Women who did not respond were given a follow-up question that used the 1999 wording, and women who did not answer the question with the 1999 wording were asked a second follow-up question that used the 1998 wording. In 2000 and 2003, 2% of women in the sample answered “2 years ago” using the 1999 wording, and they were coded as within the past 2 years. Thus, estimates for 2000 and 2003 may be slightly overestimated in comparison with estimates for years prior to 1999.

In 2005, women were asked the same series of mammography questions as in the 2000 and 2003 surveys but the skip pattern was modified so that more women were asked the follow-up question using the 1998 wording. Because additional information was available for women who replied that their last mammogram was 2 years ago, these women were not uniformly coded as having had a mammogram within the past 2 years. Thus, estimates for 2005 are more precise than estimates for 1999, 2000, and 2003 and are slightly lower than they would have been without this additional information. For example, using the improved methodology instituted in 2005, 66.8% of women aged 40 and over reported a mammogram in the past 2 years, compared with an estimate of 68.7% in 2005 using the method employed in 2000 and 2003. SAS code to categorize mammography data for 2000 and beyond is available from: http://www.cdc.gov/nchs/nhis/nhis_2005_data_release.htm.

In 2008 and 2010, the mammography questions were identical to those asked in 2005.

Mammography screening recommendations have changed over time and vary in the recommended age to begin screening and the interval for screening. For a summary of current and historic recommendations see: U.S. Preventive Services Task Force. Screening for breast cancer. Rockville, MD: Agency for Healthcare Research and Quality; 2009. Available from: http://www.uspreventiveservicestaskforce.org/uspstf/uspsbrca.htm; and see: U.S. Preventive Services Task Force. Guide to clinical preventive services, 2010–2011. Rockville, MD: Agency for Healthcare Research and Quality; 2011. Available from: http://www.ahrq.gov/clinic/pocketgd1011/.

Managed care

“Managed care” is a term originally used to refer to prepaid health plans (generally, health maintenance organizations, or HMOs) under which care is provided through a network of providers under a fixed budget and costs are “managed.” Increasingly, the term is also being used to include preferred provider organizations (PPOs) and even forms of indemnity insurance coverage (i.e., “fee-for-service” insurance).

Medicare managed care has included a combination of risk-based and cost-based plans. Risk-based plans receive a fixed prepayment per beneficiary per month to cover the cost of all covered services that a beneficiary may receive. The Centers for Medicare & Medicaid Services (CMS) announces a “benchmark” amount each year for each county for coverage of Medicare Part A and B services. A managed care plan contracting with Medicare then submits a “bid” representing its revenue needs to cover such services. If the bid is above the benchmark, this amount must be charged in a premium to the enrollees of the plan. If the bid is below the benchmark, then a portion of the difference must be used to provide additional benefits to enrollees, with the Medicare trust funds receiving the remaining share.

Cost-based plans are offered by an HMO or a competitive medical plan and receive reimbursement for their “reasonable costs” in providing Medicare services to enrollees, based on annual cost reports filed with CMS. For current definitions of the various Medicare managed care plans, see: CMS. Medicare managed care manual, ch 1, sec 30, Types of MA plans. Baltimore, MD: CMS; 2007. Available from: http://www.cms.gov/manuals/downloads/mc86c01.pdf.

Medicare enrollees have the choice to enroll in a managed care program (if available) or to receive services on a fee-for-service basis.

The two major Medicaid managed care categories are risk-based plans [managed care organizations (MCOs)] and primary care case management (PCCM) arrangements. In risk-based plans, MCOs are paid a fixed monthly fee per enrollee. The MCOs assume some or all of the financial risk for providing the services covered under the contract. PCCM providers are usually physicians, physician group practices, or entities employing or having other arrangements with such physicians but sometimes also including nurse practitioners, nurse midwives, or physician assistants. These providers (sometimes called gatekeepers) contract directly with the state to locate, coordinate, and monitor covered primary care (and sometimes additional services). PCCM providers are paid a per-patient case management fee and usually do not assume financial risk for the provision of services. Some states allow Medicaid enrollees to voluntarily enroll in managed care plans; most states require that at least certain categories of Medicaid beneficiaries join managed care plans. Within both risk-based plans and PCCM arrangements there are plans that provide specialized services to certain categories of Medicaid beneficiaries. For more information on state Medicaid managed care plans, see http://www.medicaid.gov.

[Also see Appendix II, Health maintenance organization (HMO); Medicare; Medicaid; Preferred provider organization (PPO).]

Marital status

Marital status is classified through self-reporting into the categories married and unmarried. The term “married” encompasses all married people, including those separated from their spouses. “Unmarried” includes those who are single (never married), divorced, or widowed. Prior to 1978, abortion data collected by the CDC’s Abortion Surveillance Program included separated women with unmarried women.

  • Birth file—In 1970, 39 states and the District of Columbia (D.C.), and in 1975, 38 states and D.C., included a direct question about mother’s marital status on the birth certificate. Since 1980, national estimates of births to unmarried women have been based on two methods for determining marital status: a direct question in the birth registration process and inferential procedures. In 1980–1996, marital status was reported on the birth certificates of 41–45 states and D.C.; with the addition of California in 1997, 46 states and D.C.; and in 1998–2001, 48 states and D.C. In 1997, all but four states (Connecticut, Michigan, Nevada, and New York), and in 1998, all but two states (Michigan and New York) included a direct question about mother’s marital status on their birth certificates. In 1998–2007, marital status was imputed as married on birth records with missing information in the 48 states and D.C. where this information was obtained by a direct question. In 2008–2010 for 49 states and D.C., marital status is reported in the birth registration process.
    For states lacking a direct question, marital status was inferred. Before 1980, the incidence of births to unmarried women in states with no direct question on marital status was assumed to be the same as the incidence in reporting states in the same geographic division. Starting in 1980, for states without a direct question, marital status was inferred by comparing the parents’ and child’s surnames. For 1994–1996, birth certificates in 45 states and the D.C. included a question about the mother’s marital status. Beginning in 1997, the marital status of women giving birth in California and Nevada has been determined by a direct question in the birth registration process. Beginning June 15, 1998, Connecticut discontinued inferring the mother’s marital status and added a direct question regarding mother’s marital status to the state’s birth certificate.
    In 2005, Michigan added a direct question to the birth registration process but uses inferential procedures to update information collected using the direct question. In both Michigan and New York, a birth is inferred as nonmarital if either of these factors, listed in priority-of-use order, is present: (a) a paternity acknowledgment was received or (b) the father’s name is missing. For 2006–2008 data, inferential procedures were used to compile birth statistics by marital status, in full or in part, for New York and Michigan, respectively. For 2009–2010, mother’s marital status is inferred for New York.
  • National Health Interview Survey (NHIS)—In NHIS, marital status is asked of, or about, all persons aged 14 and over. Respondents are asked, “Are you now married, widowed, divorced, separated, never married, or living with a partner?”

Maternal age

See Appendix II, Age.

Maternal education

See Appendix II, Education.

Medicaid

Medicaid was authorized in 1965 and became Title XIX of the Social Security Act. Medicaid is a jointly funded cooperative venture between the federal and state governments to assist states in the provision of adequate medical care to eligible persons. Within broad federal guidelines, each state establishes its own eligibility standards; determines the type, amount, duration, and scope of services; sets the rate of payment for services; and administers its own program.

Medicaid is the largest program providing medical and health-related services to America’s poorest people. However, Medicaid does not provide medical assistance to all persons with limited income and resources. Under the broadest provisions of the federal statute, Medicaid does not provide health care services for very poor childless adults under age 65 unless they are disabled. The major eligibility groups covered by most states include

  • Individuals who meet the requirements for the Aid to Families with Dependent Children (AFDC) program that were in effect in their state on July 16, 1996 or, at state option, more liberal criteria (with some exceptions).
  • Children under age 6 whose family income is at or below 133% of the federal poverty level.
  • Infants born to Medicaid-eligible women.
  • Pregnant women whose family income is at or below 133% of the federal poverty level (services to these women are limited to those related to pregnancy, complications of pregnancy, delivery, and postpartum care).
  • Supplemental Security Income (SSI) recipients in most states (some states use more restrictive Medicaid eligibility requirements that predate SSI).
  • Recipients of adoption or foster care assistance under Title IV of the Social Security Act.
  • Special protected groups (typically individuals who lose their cash assistance because of earnings from work or from increased Social Security benefits but who may keep Medicaid for a period of time).
  • Children who are at least age 6, but under age 19, in families with incomes at or below the federal poverty level.

States also have the option of providing Medicaid coverage for other groups.

Medicaid operates as a vendor payment program. States may pay health care providers directly on a fee-for-service basis, or states may pay for Medicaid services through various prepayment arrangements, such as through health maintenance organizations or other forms of managed care. Within federally imposed upper limits and specific restrictions, each state for the most part has broad discretion in determining the payment methodology and payment rate for services. Thus, the Medicaid program varies considerably from state to state, as well as within each state over time. For more information see: http://www.medicaid.gov/.

[Also see Appendix II, Health expenditures, national; Health insurance coverage; Health maintenance organization (HMO); Managed care; and Appendix I, Medicaid Statistical Information System (MSIS).]

Medicaid payments

Under the Medicaid program, medical vendor payments are payments (expenditures) to medical vendors from the state through a fiscal agent, or to a health insurance plan. Adjustments are made for Indian Health Service payments to Medicaid, cost settlements, third-party recoupments, refunds, voided checks, and other financial settlements that cannot be related to specific provided claims. Excluded are payments made for medical care under the emergency assistance provisions; payments made from state medical assistance funds that are not federally matchable; disproportionate-share hospital payments, cost sharing, or enrollment fees collected from recipients or a third party; and administration and training costs. Medicaid payment data presented in Health, United States are from the Medical Statistical Information System (MSIS), which obtains payment data from electronic Medicaid data submitted to the Centers for Medicare & Medicaid Services by each state. Payment data are based on adjudicated claims for medical services reimbursed with Title XIX funds.

Medical specialty

See Appendix II, Physician specialty.

Medicare

Medicare is a nationwide health insurance program providing health insurance protection to selected groups, regardless of income. The groups covered include most people aged 65 and over; people entitled to Social Security or Railroad Retirement disability benefits for at least 24 months (with limited exceptions for people with specific diagnoses); government employees with Medicare-only coverage who have been disabled for more than 29 months (with the waiting period waived or reduced in certain situations); most people with end-stage renal disease; and certain people in the Libby, Montana, vicinity who are diagnosed with asbestos-related conditions. The program was enacted July 30, 1965, as Title XVIII, Health Insurance for the Aged, of the Social Security Act, and became effective July 1, 1966. From its inception, it has included two separate but coordinated programs: hospital insurance (Part A) and supplementary medical insurance (Part B). In 1999, additional choices were allowed for delivering Medicare Part A and Part B benefits. Part C (Medicare Advantage, previously Medicare+Choice) is an expanded set of options for the delivery of health care under Medicare, created in the Balanced Budget Act passed by Congress in 1997. The term “Medicare Advantage” refers to options other than Original Medicare for receiving Part A and Part B benefits. Although all Medicare beneficiaries can receive their benefits through the original fee-for-service program, most beneficiaries enrolled in both Part A and Part B can choose to participate in a Medicare Advantage plan instead. Organizations that seek to contract as Medicare Advantage plans must meet specific organizational, financial, and other requirements. Most Medicare Advantage plans are coordinated care plans such as health maintenance organizations, preferred provider organizations, and special needs plans. Medicare Advantage plans also include private fee-for-service plans, provider-sponsored organizations, and medical savings account (MSA) plans—which provide benefits after a single high deductible is met. Medicare Advantage plans are generally paid on a capitation basis, meaning that plans are paid a predetermined amount per month per member, which is adjusted according to the health status of the plans’ members. Medicare Advantage plans are required to provide at least those services covered by Parts A and B, except hospice services. Plans may (and in certain situations must) provide extra benefits (such as vision or hearing coverage) or reduce cost-sharing or premiums.

The Medicare Prescription Drug, Improvement, and Modernization Act (also called the Medicare Modernization Act, or MMA) was passed December 8, 2003. The Medicare Prescription Drug, Improvement, and Modernization Act of 2003, Pub. L. No. 108–173, 117 Stat. 2006, established a voluntary drug benefit for Medicare beneficiaries and created a new Medicare Part D. People eligible for Medicare could begin to enroll in Part D beginning in January 2006. For more information see: http://www.medicare.gov/publications/pubs/pdf/10050.pdf and https://www.cms.gov/MedicareProgramRatesStats/downloads/MedicareMedicaidSummaries2010.pdf. [Also see Appendix II, Fee-for-service health insurance; Health insurance coverage; Health maintenance organization (HMO); Managed care; and Appendix I, Medicare Administrative Data.]

Metropolitan statistical area (MSA)

The Office of Management and Budget (OMB) defines MSAs according to published standards that are applied to U.S. Census Bureau data. The standards are revised periodically, generally prior to the decennial census, and are applied to the census data to delineate the statistical areas. Revisions to the areas are implemented between censuses by using updated population estimates. The most recent standards were released in June 2010 (available from: http://www.whitehouse.gov/sites/default/files/omb/assets/fedreg_2010/06282010_metro_standards-Complete.pdf ) but have not yet been applied to the 2010 census data. Therefore, no data presented in Health, United States are based on the 2010 standards. In the 2000 standards, an MSA is a county, or group of contiguous counties, that contains at least one urbanized area of 50,000 or more population. In addition to the county or counties that contain all or part of the urbanized area, an MSA may contain other counties if there are strong economic ties with the central county or counties, as measured by commuting. Counties that are not within an MSA are considered to be nonmetropolitan. For more information, see: http://www.census.gov/population/metro/ and http://www.whitehouse.gov/omb/bulletins_fy05_b05-02. (Also see Appendix II, Urbanization.)

For respondents to the National Health Interview Survey (NHIS), designation of place of residence as metropolitan or nonmetropolitan is based on the following MSA definitions: for 2006 and beyond, on the June 2003 OMB definitions (2000 OMB standards applied to 2000 census data); for 1995–2005, on the June 1993 OMB definitions (1990 OMB standards applied to 1990 census data); and for 1985–1994, on the June 1983 OMB definitions (1980 OMB standards applied to 1980 census data). For estimates based on 2006 NHIS data combined with earlier years of NHIS, metropolitan status of residence for all years involved is based on the June 2003 definitions. Introduction of each set of standards may create a discontinuity in trends. For example, when coding is based on the 2000 census data and standards, the percentage of the population under age 65 obtaining private insurance through the workplace in 2005 was 64.3% for persons residing within MSAs and 59.7% for persons living outside MSAs; when coding is based on the 1990 standards and 1990 census data, the percentages are 64.5% and 59.6%, respectively.

Designation of place of residence as metropolitan or nonmetropolitan for respondents to the National Immunization Survey (NIS) is based on 2000 census data and the MSAs delineated in 2003, as well as the following versions and revisions of MSA definitions: for 2011, on the December 2009 definitions; for 2010, on the November 2008 definitions, for New England, the county-based areas were used; for 2009, on the November 2007 definitions, for New England, the county-based areas were used; for 2008, on the December 2006 definitions, for New England, the county-based areas were used; for quarter 4 of 2007, on the December 2006 definitions; for quarters 1–3 of 2007, on the December 2005 definitions, for New England, the county-based areas were used in 2007; for 2006, on the November 2004 definitions, for New England, the county-based areas were used; for 2005, on the December 2003 definitions, for New England, the county-based areas were used; for quarters 3 and 4 of 2004, on the December 2003 definitions; and for quarters 1 and 2 of 2004 and quarter 4 of 2003, on the June 2003 definitions. For 2003–2004 for New England, the county-based areas were used. For more information, see: http://www.census.gov/population/metro/.

Micropolitan statistical area

The Office of Management and Budget (OMB) defines micropolitan statistical areas based on published standards that are applied to U.S. Census Bureau data. The standards are revised periodically, generally prior to the decennial census, and are applied to the census data to delineate statistical areas. Revisions to the areas are implemented between censuses using updated population estimates. A micropolitan statistical area is a nonmetropolitan county, or group of contiguous nonmetropolitan counties, that contains an urban cluster of 10,000–49,999 persons. A micropolitan statistical area may include surrounding counties if there are strong economic ties with the central county or counties as measured by commuting. Nonmetropolitan counties that are not classified as part of a micropolitan statistical area are considered noncore. For more information about micropolitan statistical areas, see http://www.census.gov/population/www/metroareas/metroarea.html. (Also see Appendix II, Urbanization.)

Multum Lexicon Plus therapeutic class

Starting with 2003 data, NCHS used Lexicon Plus (Cerner Multum, Inc., Denver, CO), a proprietary database, to assist with data editing and classification of human drugs. Starting with 2005 data, Lexicon Plus has also been used to assist with data collection. Data collected before 2003 were updated by adding a generic drug code from Lexicon Plus.

Lexicon Plus is a comprehensive database of all prescription and some nonprescription drug products available in the U.S. drug market. It uses a three-level nested category system to assign a therapeutic classification to each drug [e.g., for atenolol: cardiovascular agents (level 1); beta-adrenergic blocking agents (level 2); cardioselective beta blockers (level 3)]. Not all drugs have three classification levels; some may only have two [e.g., for diltiazem: cardiovascular agents (level 1); calcium channel blocking agents (level 2)]. Other drugs may have only one classification level. All drugs in NCHS surveys were assigned into a Lexicon Plus drug category, even those drugs not found in the Lexicon Plus drug database. “Unspecified” drugs were assigned to their respective therapeutic category (e.g., hormones/hormone modifiers– unspecified: category ID = 97, category name = hormones/hormone modifiers).

Data presented in the Health, United States Trend Table on prescription drug use by drug class are based on the second level of the Lexicon Plus nested category system (e.g., calcium channel blocking agents). A drug may have up to four drug therapeutic categories; drugs classified into more than one class were counted in each class. For example, if a person reported taking lorazepam, that respondent was classified as taking an anticonvulsant, an antiemetic/antivertigo agent, and an anxiolytic, sedative, hypnotic drug.

The drug information file is updated along with each cycle of prescription medication data release. Some new therapeutic categories could be added, and a few assigned classification levels might be changed [e.g., alendronate now has three classification levels: metabolic agents (level 1), bone resorption inhibitors (level 2), and bisphosphonates (level 3); under the prior drug information file, alendronate had two classification levels: hormones (level 1) and bisphosphonates (level 2)]. Data presented in Health, United States used the most recent drug information file for all data years.

For more information, see: http://www.cdc.gov/nchs/nhanes/nhanes1999-2000/RXQ_DRUG.htm.

N

Neonatal mortality rate

See Appendix II, Rate: Death and related rates.

Nonprofit hospital

See Appendix II, Hospital.

North American Industry Classification System (NAICS)

See Appendix II, Industry of employment.

Notifiable disease

A notifiable disease is one that, when diagnosed, health providers are required (usually by law) to report to state or local public health officials. Notifiable diseases are of public interest by reason of their contagiousness, severity, or frequency. For more information, see: http://www.cdc.gov/osels/ph_surveillance/nndss/nndsshis.htm.

Nursing home

In the Online Survey Certification and Reporting (OSCAR) database, a nursing home is a facility that is certified and meets the Centers for Medicare & Medicaid Services’ long-term care requirements for Medicare and Medicaid eligibility.

In the National Nursing Home Survey (for surveys fielded in 1995, 1997, 1999, and 2004), nursing homes have been defined as facilities that routinely provide nursing care services and have three or more beds set up for residents. Facilities may be certified by Medicare or Medicaid, or not certified but licensed by the state as a nursing home. The facilities may be freestanding or a distinct unit of a larger facility.

After October 1, 1990, long-term care facilities that met the Omnibus Budget Reconciliation Act of 1987 (Pub. L. No. 100–203, 101 Stat. 1330) nursing home reform requirements and were formerly certified under Medicaid as skilled nursing, nursing home, or intermediate care facilities were reclassified as nursing facilities. Medicare continues to certify skilled nursing facilities but not intermediate care facilities. State Medicaid programs can certify intermediate care facilities for the mentally retarded or developmentally disabled. To be certified for participation in Medicaid, nursing facilities must also be certified to participate in Medicare (except those facilities that have obtained waivers). Thus, most nursing home care is now provided in skilled care facilities.

(Also see Appendix II, Long-term care facility; Nursing home; Resident, health facility.)

Nursing home expenditures

See Appendix II, Health expenditures, national.

O

Occupancy rate

In American Hospital Association statistics, hospital occupancy rate is calculated as the average daily census divided by the number of hospital beds, cribs, and pediatric bassinets set up and staffed on the last day of the reporting period, expressed as a percentage. Average daily census is calculated by dividing the total annual number of inpatients, excluding newborns, by 365 days to derive the number of inpatients receiving care on an average day during the annual reporting period. The occupancy rate for facilities other than hospitals is calculated as the number of residents at the facility reported on the day of interview, divided by the number of reported beds. In the Online Survey Certification and Reporting (OSCAR) and the Quality Improvement Evaluation System (QIES) databases, occupancy is determined as of the day of certification inspection as the total number of residents on that day divided by the total number of beds on that day.

Office-based physician

See Appendix II, Physician.

Office visit

In the National Ambulatory Medical Care Survey, a physician’s ambulatory practice (office) can be in any location other than in a hospital, nursing home, other extended care facility, patient’s home, industrial clinic, college clinic, or family planning clinic. Offices in health maintenance organizations and private offices in hospitals are included. An office visit is any direct personal exchange between an ambulatory patient and a physician or members of his or her staff for the purpose of seeking care and rendering health services. (Also see Appendix II, Outpatient visit.)

Outpatient department

According to the National Hospital Ambulatory Medical Care Survey (NHAMCS), an outpatient department (OPD) is a hospital facility where nonurgent ambulatory medical care is provided. The following types of OPDs are excluded from NHAMCS: ambulatory surgical centers, chemotherapy, employee health services, renal dialysis, methadone maintenance, and radiology. (Also see Appendix II, Emergency department; Outpatient visit.)

Outpatient surgery

According to the American Hospital Association, outpatient surgery is a surgical operation, whether major or minor, performed on a patient who does not remain in the hospital overnight. Outpatient surgery may be performed in inpatient operating suites, outpatient surgery suites, or procedure rooms within an outpatient care facility. A surgical operation involving more than one surgical procedure is considered one surgical operation. (Also see Appendix II, Procedure.)

Outpatient visit

The American Hospital Association defines outpatient visits as visits for receipt of medical, dental, or other services at a hospital by patients who are not lodged in the hospital. Each appearance by an outpatient to each unit of the hospital is counted individually as an outpatient visit, including all clinic visits, referred visits, observation services, outpatient surgeries, and emergency department visits. In the National Hospital Ambulatory Medical Care Survey, an outpatient department visit is a direct personal exchange between a patient and a physician or other health care provider working under the physician’s supervision for the purpose of seeking care and receiving personal health services. (Also see Appendix II, Emergency department or emergency room visit; Outpatient department.)

P

Pap smear

A Pap smear (also known as a Papanicolaou smear or Pap test) is a microscopic examination of cells scraped from the cervix that is used to detect cancerous or precancerous conditions of the cervix or other medical conditions.

In the National Health Interview Survey (NHIS), questions concerning Pap smear use were asked on an intermittent schedule, and the question content differed slightly across years. In 1987, women were asked to report when they had their most recent Pap smear, in days, weeks, months, or years. Women who did not respond were asked a follow-up question, “Was it 3 years ago or less, between 3 and 5 years, or 5 years or more ago?” Pap smear data in the past 3 years were not available in 1990 and 1991. In 1993 and 1994, women were asked whether they had a Pap smear within the past year, between 1 and 3 years ago, or more than 3 years ago. In 1998, women were asked whether they had a Pap smear 1 year ago or less, more than 1 year but not more than 2 years ago, more than 2 years but not more than 3 years ago, more than 3 years but not more than 5 years ago, or more than 5 years ago.

In 1999, women were asked when they had their most recent Pap smear, in days, weeks, months, or years. Four percent of women in the sample responded “3 years ago.” In Health, United States, these women were coded as within the past 3 years, although a response of 3 years ago may include women whose last Pap smear was more than 3 but less than 4 years ago. Thus, estimates for 1999 may be overestimated to some degree in comparison with estimates for previous years.

In 2000 and 2003, women were asked when they had their most recent Pap smear (give month and year). Women who did not respond were given a follow-up question that used the 1999 wording, and women who did not answer the follow-up question were asked a second follow-up question that used the 1998 wording. In 2000 and 2003, less than 1% of women in the sample answered “3 years ago” using the 1999 wording, and they were coded as within the past 3 years. Therefore, estimates for 2000 and 2003 may be slightly overestimated in comparison with estimates for years prior to 1999.

In 2005, women were asked the same series of questions about Pap smear use as in the 2000 and 2003 surveys, but the skip pattern was modified so that more women were asked the follow-up question using the 1998 wording. Because additional information was available for women who replied that their last Pap smear was 3 years ago, these women were not uniformly coded as having had a Pap smear within the past 3 years. Thus, estimates for 2005 are more precise than estimates for 1999, 2000, and 2003 and are slightly lower than they would have been without this additional information. For example, using the improved methodology instituted in 2005, 77.7% of women aged 18 and over reported a Pap smear in the past 3 years, compared with an estimate of 78.3% in 2005 using the method employed in 2000 and 2003. SAS code to categorize Pap smear data for 2000 and beyond is available from: http://www.cdc.gov/nchs/nhis/nhis_2005_data_release.htm.

In 2008 and 2010, Pap smear questions were similar to those asked in 2005.

All women aged 18 and over are asked the Pap smear question(s). In some data years, a series of questions was asked that also included information about hysterectomy. Women who reported having had a hysterectomy (removal of the uterus, with or without removal of the ovaries and cervix) were still asked the Pap smear questions because a woman who has had a hysterectomy may still have Pap smear testing.

The U.S. Preventive Services Task Force recommends against routine Pap smear screening in women who have had a total hysterectomy for benign disease. Therefore, two measures of Pap smear screening are presented in Health, United States: one among all women and one among women who did not report having a hysterectomy, although it is not known from NHIS data whether the hysterectomy was for benign disease. Questions about whether the respondent had a hysterectomy were not asked in 2003. For other survey years, questions about hysterectomy in NHIS differed slightly. In 1987, women who reported that they had not had a recent Pap smear were asked the most important reason they had not had a Pap smear. One reason women could select was because they had had a hysterectomy. In 1993, 1994, 1998, and 1999, women were asked, “Have you had a hysterectomy?” In 2000, 2005, 2008, and 2010, two questions were used to determine whether women had had a hysterectomy. Women were asked, “Have you had a hysterectomy?” In addition, women who reported that they had not had a recent Pap smear were asked the most important reason they had not had a Pap smear. One reason women could select was because they had had a hysterectomy. Women indicating in either of these questions that they had had a hysterectomy were excluded from the Pap smear screening estimates.

Pap smear screening recommendations have changed over time and vary in the recommended age to begin and end screening and the interval for screening. For a summary of current and historic recommendations, see: U.S. Preventive Services Task Force. Screening for cervical cancer: Rockville, MD: Agency for Healthcare Research and Quality; 2012. Available from: http://www.uspreventiveservicestaskforce.org/uspstf/uspscerv.htm; and see: U.S. Preventive Services Task Force. Guide to clinical preventive services, 2010–2011. Rockville, MD: Agency for Healthcare Research and Quality; 2011. Available from: http://www.ahrq.gov/clinic/pocketgd.htm.

Perinatal mortality rate; ratio

See Appendix II, Rate: Death and related rates.

Personal care home with or without nursing

See Appendix II, Nursing home.

Personal health care expenditures

See Appendix II, Health expenditures, national.

Physical activity, leisure-time

Starting with Health, United States, 2010, estimates on leisure-time physical activity changed to reflect the federal 2008 Physical Activity Guidelines for Americans (available from: http://www.health.gov/PAGuidelines/guidelines/default.aspx). Adults who met the 2008 guidelines reported at least 150 minutes per week of moderate-intensity or 75 minutes per week of vigorous-intensity aerobic physical activity (or an equivalent combination of moderate- and vigorous-intensity aerobic activity) and muscle strengthening activities at least twice a week. The estimates for the percentage of Americans who met the 2008 guidelines for aerobic and muscle strengthening are not comparable with estimates shown in previous editions of Health, United States that showed the percentage of Americans with regular leisure-time physical activity. For more information, see: Carlson SA, Fulton JE, Schoenborn CA, Loustalot F. Trend and prevalence estimates based on the 2008 Physical Activity Guidelines for Americans. Am J Prev Med 2010;39(4)305–13.

Starting with 1998 data, leisure-time physical activity has been assessed in the National Health Interview Survey (NHIS) by asking adults a series of questions about how often they do vigorous or light/moderate physical activity of at least 10 minutes duration and about how long these sessions generally last. All questions related to leisure-time physical activity were phrased in terms of current behavior and lack a specific reference period. Vigorous physical activity is described as causing heavy sweating or a large increase in breathing or heart rate, and light/moderate as causing light sweating or a slight to moderate increase in breathing or heart rate. Adults were also asked about how often they did leisure-time physical activities specifically designed to strengthen their muscles, such as lifting weights or doing calisthenics. For more information, see the NHIS physical activity website at: http://www.cdc.gov/nchs/nhis/physical_activity.htm.

Physician

Data on physician characteristics are obtained through physician self-report from the American Medical Association’s (AMA) Physician Masterfile. Although the AMA collects data for both doctors of medicine (MDs) and doctors of osteopathy (DOs), in Health, United States data for DOs come from the American Osteopathic Association.

  • Active (or professionally active) physician—These physicians are currently engaged in patient care or other professional activity for a minimum of 20 hours per week. Other professional activity includes administration, medical teaching, research, and other activities such as employment with insurance carriers, pharmaceutical companies, corporations, voluntary organizations, and medical societies. Physicians who are retired, semiretired, working part-time, or not practicing are classified as inactive and are excluded. Also excluded are physicians with unknown address and physicians who did not provide information on type of practice or present employment (not classified).
  • Hospital-based physician—These physicians are employed under contract with hospitals to provide direct patient care and include physicians in residency training (including clinical fellows) and full-time members of the hospital staff.
  • Office-based physician—These physicians are engaged in seeing patients in solo practice, group practice, two-physician practice, other patient care employment, or in providing inpatient services such as those offered by pathologists and radiologists.
    Data for physicians are presented by type of education (doctor of medicine or doctor of osteopathy); place of education (U.S. medical graduates and international medical graduates); activity status (professionally active and inactive); area of specialty; and geographic area. (Also see Appendix II, Physician specialty.)

Physician specialty

A physician specialty is any specific branch of medicine in which a physician may concentrate. Data are based on physician self-reports of their primary area of specialty. Physician data are broadly categorized into two areas of practice: those who provide primary care and those who provide specialty care.

  • Primary care generalist—These physicians practice in the general fields of family medicine, general practice, internal medicine, obstetrics and gynecology, and pediatrics. Specifically excluded are primary care specialists associated with these generalist fields.
  • Primary care specialist—These specialists practice in the primary care subspecialties of family medicine, internal medicine, obstetrics and gynecology, and pediatrics. Family medicine subspecialties include geriatric medicine and sports medicine. Internal medicine subspecialties include adolescent medicine, critical care medicine, diabetes, endocrinology, diabetes and metabolism, hematology, hepatology, hematology/oncology, cardiac electrophysiology, infectious diseases, clinical and laboratory immunology, geriatric medicine, sports medicine, nephrology, nutrition, medical oncology, pulmonary critical care medicine, and rheumatology. Obstetrics and gynecology subspecialties include hospice and palliative medicine (obstetrics and gynecology), maternal and fetal medicine, critical care medicine (obstetrics and gynecology), and reproductive endocrinology. Pediatric subspecialties include adolescent medicine, pediatric critical care medicine, pediatrics/internal medicine, neonatal–perinatal medicine, pediatric allergy, pediatric cardiology, pediatric endocrinology, pediatric infectious disease, pediatric pulmonology, medical toxicology (pediatrics), pediatric emergency medicine, pediatric gastroenterology, pediatric hematology/oncology, clinical and laboratory immunology (pediatrics), pediatric nephrology, pediatric rheumatology, and sports medicine (pediatrics).
  • Specialty care physician—These physicians are sometimes called specialists and include primary care specialists listed above in addition to all other physicians not included in the generalist definition. Specialty fields include allergy and immunology, aerospace medicine, anesthesiology, cardiovascular diseases, child and adolescent psychiatry, colon and rectal surgery, dermatology, diagnostic radiology, forensic pathology, gastroenterology, general surgery, medical genetics, neurology, nuclear medicine, neurological surgery, occupational medicine, ophthalmology, orthopedic surgery, otolaryngology, psychiatry, public health and general preventive medicine, physical medicine and rehabilitation, plastic surgery, anatomic and clinical pathology, pulmonary diseases, radiation oncology, thoracic surgery, urology, addiction medicine, critical care medicine, legal medicine, and clinical pharmacology.

(Also see Appendix II, Physician.)

Population

The U.S. Census Bureau collects and publishes data on populations in the United States according to several different definitions. Various statistical systems then use the appropriate population for calculating rates. (Also see Appendix I, Population Census and Population Estimates.)

  • Resident population includes persons whose usual place of residence (i.e., the place where one usually lives and sleeps) is in one of the 50 states or the District of Columbia. It includes members of the Armed Forces stationed in the United States and their families. It excludes members of the Armed Forces stationed outside the United States and civilian U.S. citizens whose usual place of residence is outside the United States. The resident population is the denominator for calculating birth and death rates and incidence of disease.
  • Civilian population is the resident population excluding members of the Armed Forces, although families of members of the Armed Forces are included. The civilian population is the denominator for rates calculated for the National Hospital Discharge Survey and for emergency department visit rates using the National Hospital Ambulatory Medical Care Survey—Emergency Department Component.
  • Civilian noninstitutionalized population is the civilian population excluding persons residing in institutions (such as nursing homes, prisons, jails, mental hospitals, and juvenile correctional facilities). U.S. Census Bureau estimates of the civilian noninstitutionalized population are used to calculate sample weights for the National Health Interview Survey, the National Health and Nutrition Examination Survey, and the National Survey of Family Growth, and as denominators for rates calculated for the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey—Outpatient Department Component.

Postneonatal mortality rate

See Appendix II, Rate: Death and related rates.

Poverty

Poverty statistics are based on definitions originally developed by the Social Security Administration. These include a set of money income thresholds that vary by family size and composition. Families or individuals with income below the appropriate threshold are classified as below poverty. These thresholds are updated annually by the U.S. Census Bureau, using the change in the average annual Consumer Price Index for all urban consumers (CPI–U). For example, the average poverty threshold for a family of four was $23,021 in 2011, $22,314 in 2010, $17,603 in 2000, and $13,359 in 1990. For more information, see: U.S. Census Bureau. Annual poverty thresholds. Available from: http://www.census.gov/hhes/www/poverty/data/threshld/index.html; and DeNavas-Walt C, Proctor BD, Smith JC. Income, poverty, and health insurance coverage in the United States: 2011. U.S. Census Bureau Current Population Report, P60–243. Washington, DC: U.S. Government Printing Office; 2012. Available from: http://www.census.gov/prod/2012pubs/p60-243.pdf. Also see the U.S. Census Bureau’s poverty website at: http://www.census.gov/hhes/www/poverty/poverty.html.

  • National Health Interview Survey (NHIS) and National Health and Nutrition Examination Survey (NHANES)—For data years prior to 1997, percent of poverty level was based on family income and family size using U.S. Census Bureau poverty thresholds. Starting with 1997 data, percent of poverty level has been based on family income, family size, number of children in the family, and, for families with two or fewer adults, the age of the adults in the family. Percent of poverty level in NHANES is also based on family income and family size and composition. [Also see Appendix II, Consumer Price Index (CPI); Family income; and Appendix I, Current Population Survey (CPS); National Health Interview Survey (NHIS); National Health and Nutrition Examination Survey (NHANES).]
  • National Survey of Children’s Health (NSCH)—Percent of poverty level was based on total household income and family composition using U.S. Census Bureau poverty thresholds. Two variables were used to determine household poverty status: the number of people residing in a household and the total household income during the prior year. If either of these components was missing, the information was imputed so that poverty level could be calculated.
    The poverty categories available in the two survey years presented inHealth, United States used slightly different cut points. In 2003, the available categories were: below 100%, 100%–199%, 200%–399%, and 400% or more. In 2007, the poverty categories were: at or below 100%, above 100% to 200%, above 200% to 400%, and above 400%.

Preferred provider organization (PPO)

A PPO is a type of medical plan in which coverage is provided to participants through a network of selected health care providers, such as hospitals and physicians. Enrollees may seek care outside the network but pay a greater percentage of the cost of coverage than within the network. [Also see Appendix II, Health maintenance organization (HMO); Managed care]

Prenatal care

Prenatal care is medical care provided to a pregnant woman to prevent complications and decrease the incidence of prenatal mortality. Information on when pregnancy care began is recorded on the birth certificate. Between 1970 and 1980, the reporting area for prenatal care expanded. In 1970, 39 states and the District of Columbia (D.C.) reported prenatal care on the birth certificate. Data were not available from Alabama, Alaska, Arkansas, Connecticut, Delaware, Georgia, Idaho, Massachusetts, New Mexico, Pennsylvania, and Virginia. In 1975, data were available from three additional states (Connecticut, Delaware, and Georgia), increasing the number of states reporting prenatal care to 42 and D.C. During 1980–2002, prenatal care information was available for the entire United States.

Starting in 2003, some states began implementation of the 2003 revision of the U.S. Standard Certificate of Live Birth. The prenatal care item on the 2003 revision of the certificate asks for the date of first prenatal visit, whereas the prenatal care item on the 1989 revision asks for the month prenatal care began. In addition, the 2003 revision recommends that information on prenatal care be gathered from prenatal care or medical records, whereas the 1989 revision did not recommend a source for these data. Data on prenatal care from the 2003 revision of the birth certificate are not comparable with data from the 1989 revision.

Prevalence

Prevalence is the number of cases of a disease, number of infected persons, or number of persons with some other attribute present during a particular interval of time. It is often expressed as a rate (e.g., the prevalence of diabetes per 1,000 persons during a year). (Also see Appendix II, Incidence.)

Primary care specialty

See Appendix II, Physician specialty.

Procedure

Procedures can include surgical procedures (such as appendectomy), diagnostic procedures (such as spinal tap), and therapeutic treatments (such as infusion of a cancer chemotherapeutic substance) reported on a patient’s medical record. Procedures are coded according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD–9–CM).

  • National Hospital Discharge Survey (NHDS)—In NHDS, up to four different procedures are coded per hospital stay; starting with 2010 data, up to eight different procedures are coded. Common procedures were identified by procedure code or, where appropriate, by groups of procedure codes (Table XI). Procedures per hospital stay can be counted in different ways depending on the type of data of interest. Counting any-listed procedures means that if one or more of the same procedure occurs during the hospital stay, it is only counted once, so any-listed counts will generally be equivalent to the number of hospital stays during which a procedure was performed. Counting all-listed procedures means that if the same procedure occurs multiple times during a hospital stay it is counted each time it occurs, up to the maximum of four available codes, to maintain consistency across all of the data years shown inHealth, United States; thus, all-listed procedure counts can be greater than the number of hospital stays with a procedure. InHealth, United States, NHDS procedure data are presented for any-listed procedures.
  • Healthcare Cost and Utilization Project, Nationwide Inpatient Sample (HCUP–NIS)—Up to 15 procedures are coded per hospital stay in the HCUP–NIS database. For each record, a principal procedure is identified as the first procedure listed. HCUP–NIS procedure data presented inHealth, United States are limited to operating room procedures that are principal procedures (first-listed). Valid operating room procedures were identified according to diagnosis-related groups (DRGs). For DRGs, physician panels classify all ICD–9–CM procedure codes based on whether the procedure would be performed in operating rooms in most hospitals. Clinical Classifications Software (CCS) was used to categorize ICD–9–CM principal operating room procedure codes into one of 231 clinically meaningful categories. CCS was developed at the Agency for Healthcare Research and Quality as a tool for clustering patient procedures into a manageable number of clinically meaningful categories. For more information on CCS, see: http://www.hcup-us.ahrq.gov/toolssoftware/ccs/AppendixBSinglePR.txt. The top-ranking operating room procedure categories by age group, based on the number of discharges and total national costs, are presented inHealth, United States (Table XII). CCS categories labeled “other” are not presented because these comprise miscellaneous procedures and that do not form a homogenous group.

(Also see Appendix II, Outpatient surgery.)

Proprietary hospital

See Appendix II, Hospital.

Purchasing power parities (PPPs)

PPPs are calculated rates of currency conversion that equalize the purchasing power of different currencies by eliminating the differences in price levels between countries. PPPs show the ratio of prices in national currencies for the same good or service in different countries. PPPs can be used to make intercountry comparisons of the gross domestic product (GDP) and its component expenditures. [Also see Appendix II, Gross domestic product (GDP).]

R

Race

In 1977, the Office of Management and Budget (OMB) issued “Race and Ethnic Standards for Federal Statistics and Administrative Reporting” (Statistical Policy Directive 15) to promote comparability of data among federal data systems. The 1977 Standards called for the federal government’s data systems to classify individuals into the following four racial groups: American Indian or Alaska Native, Asian or Pacific Islander, black, and white. Depending on the data source, the classification by race was based on self-classification or on observation by an interviewer or other person filling out the questionnaire.

In 1997, revisions were announced for classification of individuals by race within the federal government’s data systems. [See: Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity. Fed Regist 1997 October 30;62(210):58781–90.] The 1997 Standards specify five racial groups: American Indian or Alaska Native, Asian, black or African American, Native Hawaiian or Other Pacific Islander, and white. These five categories are the minimum set for data on race in federal statistics. The 1997 Standards also offer an opportunity for respondents to select more than one of the five groups, leading to many possible multiple-race categories. As with the single-race groups, data for the multiple-race groups are to be reported when estimates meet agency requirements for reliability and confidentiality. The 1997 Standards allow for observer or proxy identification of race but clearly state a preference for self-classification. The federal government considers race and Hispanic origin to be two separate and distinct concepts. Thus, Hispanic persons may be of any race. Federal data systems were required to comply with the 1997 Standards by 2003.

  • National Health Interview Survey (NHIS)—Starting with Health, United States, 2002, race-specific estimates based on NHIS were tabulated using the 1997 Standards for data year 1999 and beyond and are not strictly comparable with estimates for earlier years. The 1997 Standards specify five single-race categories plus multiple-race categories. Estimates for specific race groups are shown when they meet requirements for statistical reliability and confidentiality. The race categories white only, black or African American only, American Indian or Alaska Native only, Asian only, and Native Hawaiian or Other Pacific Islander only include persons who reported only one racial group; the category 2 or more races includes persons who reported more than one of the five racial groups in the 1997 Standards or one of the five racial groups and “some other race.” Prior to data year 1999, data were tabulated according to the 1977 Standards, with four racial groups, and the Asian only category included Native Hawaiian or Other Pacific Islander. Estimates for single-race categories prior to 1999 included persons who reported one race or, if they reported more than one race, identified one race as best representing their race. Differences between estimates tabulated using the two standards for data year 1999 are discussed in the footnotes for each NHIS table inHealth, United States 2002, 2003, and 2004 editions. Available from: http://www.cdc.gov/nchs/hus/previous.htm#editions.
    Tables XIII and XIV illustrate NHIS data tabulated by race and Hispanic origin according to the 1997 and 1977 Standards for two health statistics (cigarette smoking and private health insurance coverage). In these examples, three separate tabulations using the 1997 Standards are shown: (a) Race: mutually exclusive race groups, including several multiple-race combinations; (b) Race, any mention: race groups that are not mutually exclusive because each race category includes all persons who mention that race; and (c) Hispanic origin and race: detailed race and Hispanic origin with a multiple-race total category. Where applicable, comparison tabulations by race and Hispanic origin are shown based on the 1977 Standards. Because there are more race groups with the 1997 Standards, the sample size of each race group under the 1997 Standards is slightly smaller than the sample size under the 1977 Standards. Only those few multiple-race groups with sufficient numbers of observations to meet standards of statistical reliability are shown. The tables also illustrate changes in labels and group categories resulting from the 1997 Standards. The race designation black was changed to black or African American, and the ethnicity designation Hispanic was changed to Hispanic or Latino.
    Data systems included inHealth, United States, other than NHIS, the National Survey of Drug Use & Health (NSDUH), and the National Health and Nutrition Examination Survey (NHANES), generally do not permit tabulation of estimates for the detailed race and ethnicity categories shown in Tables XIII and XIV, either because race data based on the 1997 Standards categories are not yet available or because there are insufficient numbers of observations in certain subpopulation groups to meet statistical reliability or confidentiality requirements.
    To improve the quality of data on ethnicity and race in NHIS, hot-deck imputation of selected race and ethnicity variables was done for the first time in the 2000 NHIS and continued to be used for subsequent data years. Starting with 2003 data, records for persons for whom “other race” was the only race response were treated as having missing data on race and were added to the pool of records for which selected race and ethnicity variables were imputed. Prior to the 2000 NHIS, a crude imputation method that assigned a race to persons with missing values for the variable MAINRACE (the respondent’s classification of the race he or she most identified with) was used. Under these procedures, if an observed race was recorded by the interviewer, it was used to code a race value. If there was no observed race value, all persons who had a missing value for MAINRACE and were identified as Hispanic on the Hispanic origin question were coded as white. In all other cases, non-Hispanic persons were coded as “other race.” Additional information on the NHIS methodology for imputing race and ethnicity is available from the survey documentation at: http://www.cdc.gov/nchs/nhis/quest_data_related_1997_forward.htm and from the NHIS race and Hispanic origin home page at: http://www.cdc.gov/nchs/nhis/rhoi.htm.
  • National Health and Nutrition Examination Survey (NHANES)—Starting with Health, United States, 2003, race-specific estimates based on NHANES were tabulated using the 1997 Standards for data years 1999 and beyond. Prior to data year 1999, the 1977 Standards were used. Because of the differences between the two standards, the race-specific estimates shown in Trend Tables based on NHANES for 1999–2004 are not strictly comparable with estimates for earlier years. Race in NHANES I and II was determined primarily by interviewer observation; starting with NHANES III, race was self-reported by survey participants.
    The NHANES sample for data years 1999–2006 was designed to provide estimates specifically for persons of Mexican origin and not for all Hispanic-origin persons in the United States. Persons of Hispanic origin other than Mexican were entered into the sample with different selection probabilities that are not nationally representative of the total U.S. Hispanic population. Starting with 2007–2008 data, all Hispanic persons were oversampled, not just Mexican American persons. Estimates are shown for non-Hispanic white, non-Hispanic black, and Mexican-origin persons. Although data were collected according to the 1997 Standards, there are insufficient numbers of observations to meet statistical reliability or confidentiality requirements for reporting estimates for additional race categories.
  • National Survey on Drug Use & Health (NSDUH)—Race-specific estimates based on NSDUH are tabulated using the 1997 Standards. Estimates in the NSDUH Trend Table begin with data year 2002. Estimates for specific race groups are shown when they meet requirements for statistical reliability and confidentiality. The race categories white only, black or African American only, American Indian or Alaska Native only, Asian only, and Native Hawaiian or Other Pacific Islander only include persons who reported only one racial group; the category two or more races includes persons who reported more than one of the five racial groups in the 1997 Standards or one of the five racial groups and “some other race.”
  • National Vital Statistics System (NVSS)—Some of the states in the Vital Statistics Cooperative Program are still revising their birth and death records to conform to the 1997 Standards on race and ethnicity. During the transition to full implementation of the 1997 Standards, vital statistics data will continue to be presented for four major race groups (white, black or African American, American Indian or Alaska Native, and Asian or Pacific Islander) in accordance with the 1977 Standards.
  • Birth file—Information about the race and Hispanic origin of the mother and father are provided by the mother at the time of birth and are recorded on the birth certificate or fetal death record. Since 1980, birth rates, birth characteristics, and death rates for live-born infants and fetal deaths are presented inHealth, United States according to race of the mother. Before 1980, data were tabulated by race of the newborn and fetus, taking into account the race of both parents. If the parents were of different races and one parent was white, the child was classified according to the race of the other parent. When neither parent was white, the child was classified according to father’s race, with one exception: if either parent was Hawaiian, the child was classified Hawaiian. Before 1964, if race was unknown, the birth was classified as white. Starting in 1964, unknown race was classified according to information on the birth record. Starting with the 2000 census, the race and ethnicity data used for denominators (population) to calculate birth and fertility rates have been collected in accordance with the 1997 revised OMB standards for race and ethnicity. However, the numerators (births) will not be compatible with the denominators until all the states revise their birth certificates to reflect the new standards. To compute rates, it is currently necessary to bridge population data for multiple-race persons to single-race categories. (Also see Appendix I, Population Census and Population Estimates, Bridged-race Population Estimates for Census 2000.)
    Starting with 2003 data, some states began using the 2003 revision of the U.S. Standard Certificate of Live Birth, which allows the reporting of more than one race (multiple races). For 2010 data, 38 states and the District of Columbia (D.C.) allowed the reporting of multiple-race data (34 states and D.C. used the 2003 revision of the U.S. Standard Certificate of Live Birth and 3 states used the 1989 revision). These 38 states and D.C. represented 83% of all U.S. resident births. In 2010, multiple race was reported for approximately 2% of mothers in the states that permitted reporting of more than one race. In 2010, data from the vital records of the remaining 12 states followed the 1977 OMB Standards and reported the minimum set of four race categories, compared with the minimum of five race categories for the 1997 Standards. To provide uniformity and comparability of the data during the transition period, before multiple-race data are available for all reporting areas, the responses of those who reported more than one race must be bridged to a single race. For more information on the adoption of the 2003 revision of the U.S. Standard Certificate of Live Birth, see the Technical Notes section of the annual series of “Births: Final Data” reports, available from: http://www.cdc.gov/nchs/products/nvsr.htm.
    Although the bridging procedure imputes multiple race of mothers to one of the four minimum races stipulated in the 1977 Standards, mothers of a specified Asian or Pacific Islander (API) subgroup (Chinese, Japanese, Hawaiian, or Filipino) in combination with another race (American Indian or Alaska Native, black, and/or white) or another API subgroup cannot be imputed to a single API subgroup. Data for the API subgroups are available in the 2010 Natality Public-use data file at: http://www.cdc.gov/nchs/births.htm.
  • Mortality file—Information about the race and Hispanic origin of a decedent is reported by the funeral director as provided by an informant (often the surviving next of kin), or in the absence of an informant, on the basis of observation. Death rates by race and Hispanic origin are based on information from death certificates (numerators of the rates) and on population estimates from the Census Bureau (denominators). Race and ethnicity information from the census is by self-report. To the extent that race and Hispanic origin are inconsistent between these two data sources, death rates will be biased. Studies have shown that persons self-reported as American Indian, Asian, or Hispanic on census and survey records may sometimes be reported as white or non-Hispanic on the death certificate, resulting in an underestimation of deaths and death rates for the American Indian, Asian, and Hispanic groups. Bias also results from undercounts of some population groups in the census—particularly young black males, young white males, and elderly persons—resulting in an overestimation of death rates. The net effects of misclassification and undercoverage result in overstated death rates for the white population and the black population, estimated to be 1% and 5%, respectively. Understated death rates for other population groups are estimated as follows: American Indian, 21%; Asian or Pacific Islander, 11%; and Hispanic, 2%. For more information, see: Rosenberg HM, Maurer JD, Sorlie PD, et al. Quality of death rates by race and Hispanic origin: A summary of current research, 1999. NCHS. Vital Health Stat 1999;2(128). Available from: http://www.cdc.gov/nchs/data/series/sr_02/sr02_128.pdf; and Arias E, Schauman WS, Eschbach K, et al. The validity of race and Hispanic origin reporting on death certificates in the United States. NCHS. Vital Health Stat 2008;2(148). Available from: http://www.cdc.gov/nchs/data/series/sr_02/sr02_148.pdf.
    Denominators for infant mortality rates are based on the number of live births, rather than on population estimates. Race information for the denominator is supplied from the birth certificate. Before 1980, race of child for the denominator took into account the races of both parents. Starting in 1980, race information for the denominator has been based solely on the race of the mother. Race information for the numerator is supplied from the death certificate. For the infant mortality rate, race information for the numerator is race of the deceased child.
    Issues affecting the interpretation of vital event rates for the American Indian or Alaska Native population include (a) the presence of two enumeration techniques for estimating the American Indian or Alaska Native population, (b) changes in the classification or self-identification of American Indian or Alaska Native heritage over time, and (c) misclassification of American Indian or Alaska Native persons on death certificates. Vital event rates for the American Indian or Alaska Native population shown inHealth, United States are based on the total U.S. resident American Indian and Alaska Native population, as enumerated by the U.S. Census Bureau. In contrast, the Indian Health Service calculates vital event rates for this population based on U.S. Census Bureau county data for American Indian and Alaska Native persons who reside on or near reservations. Interpretation of trends for the American Indian and Alaska Native population should take into account that population estimates for these groups increased 45% between 1980 and 1990, partly because of better enumeration techniques in the 1990 decennial census and the increased tendency for people to identify themselves as American Indian in 1990. Because of misclassification of American Indian and Alaska Native persons on death certificates (for some states, estimated at greater than 10%), or no information on misclassification, American Indian or Alaska Native state-specific mortality estimates published inHealth, United States should be interpreted with caution.
    Interpretation of trends for the Asian population in the United States should take into account that this population more than doubled between 1980 and 1990, primarily because of immigration. Between 1990 and 2000, the increase in the Asian population was 48% for persons reporting that they were Asian alone and 72% for persons who reported they were either Asian alone or Asian in combination with another race.
    For more information on coding race by using vital statistics, see: NCHS. Vital statistics of the United States, vol I, Natality, and vol II, Mortality, part A, Technical appendix. Hyattsville, MD; published annually. Available from: http://www.cdc.gov/nchs/nvss.htm.
    Starting with 2003 data, some states began using the 2003 revision of the U.S. Standard Certificate of Death, which allows the reporting of more than one race (multiple races). This change was implemented to reflect the increasing diversity of the U.S. population and to be consistent with the decennial census. In 2010, 34 states and D.C. reported multiple-race data. For more information on states reporting of multiple-race data, see the annual series of “Deaths: Final Data” reports, available from: http://www.cdc.gov/nchs/products/nvsr.htm.
    To provide uniformity and comparability of data until all states are reporting multiple-race data, it has been necessary to bridge the responses of those for whom more than one race is reported (multiple race) to one single race. For more information, see: NCHS procedures for multiple-race and Hispanic origin data: Collection, coding, editing, and transmitting. Hyattsville, MD: NCHS; 2004. Available from: http://www.cdc.gov/nchs/data/dvs/Multiple_race_docu_5-10-04.pdf; and NCHS. Vital statistics of the United States, vol I, Natality, and vol II, Mortality, part A, Technical appendix. Hyattsville, MD; published annually. Available from: http://www.cdc.gov/nchs/nvss.htm.
  • Youth Risk Behavior Survey (YRBS)—Prior to 1999, the 1977 OMB Standards were used. Respondents could select only one of the following categories: white (not Hispanic), black (not Hispanic), Hispanic or Latino, Asian or Pacific Islander, American Indian or Alaska Native, or other. Beginning in 1999, the 1997 OMB Standards were used for race-specific estimates, and respondents were given the option of selecting more than one category to describe their race and ethnicity. Between 1999 and 2003, students were asked a single question about race and Hispanic origin, with the option of choosing more than one of the following responses: white, black or African American, Hispanic or Latino, Asian, Native Hawaiian or Other Pacific Islander, or American Indian or Alaska Native. In 2005, students were asked a question about Hispanic origin (“Are you Hispanic or Latino?”) and a second separate question about race that included the option of selecting more than one of the following categories: American Indian or Alaska Native, Asian, black or African American, Native Hawaiian or Other Pacific Islander, or white. Because of the differences between questions, data about race and Hispanic ethnicity for the years prior to 1999 are not strictly comparable with estimates for the later years. However, analyses of data collected between 1991 and 2003 have indicated that the data are comparable across years and can be used to study trends.
    See: Brener ND, Kann L, McManus T. A comparison of two survey questions on race and ethnicity among high school students. Public Opin Q 2003;67(2):227–36.

Rate

A rate is a measure of some event, disease, or condition in relation to a unit of population, along with some specification of time. (Also see Appendix II, Age adjustment; Population.)

■. Birth and related rates

  • Birth rate is calculated by dividing the number of live births in a population in a year by the resident population. For census years, rates are based on unrounded census counts of the resident population as of April 1. For the noncensus years 1981–1989, rates are based on national estimates of the resident population as of July 1, rounded to thousands. Rounded population estimates for 5-year age groups are calculated by summing unrounded population estimates before rounding to thousands. Starting in 1991, rates are based on unrounded national population estimates. Birth rates for 1991–1999 were revised based on the 1990 and 2000 censuses. The rates for 1990 and 2000 are based on populations from the censuses in those years as of April 1. Birth rates for 2001–2009 were revised based on the 2000 and 2010 censuses. The population estimates have been provided by the U.S. Census Bureau and are based on the 2000 census counts by age, race, and sex, which have been modified to be consistent with OMB racial categories as of 1977 and historical categories for birth data. Beginning in 1997, the birth rate for the maternal age group 45–49 includes data for mothers aged 50–54 in the numerator and is based on the population of women aged 45–49 in the denominator. Birth rates are expressed as the number of live births per 1,000 population. The rate may be restricted to births to women of specific age, race, marital status, or geographic location (specific rate), or it may be related to the entire population (crude rate).
  • Fertility rate is the total number of live births, regardless of the age of the mother, per 1,000 women of reproductive age (15–44 years). Beginning in 1997, the birth rate for the maternal age group 45–49 includes data for mothers aged 50–54 in the numerator and is based on the population of women aged 45–49 in the denominator.

■. Death and related rates

  • Death rate is calculated by dividing the number of deaths in a population in a year by the midyear resident population. For census years, rates are based on unrounded census counts of the resident population as of April 1. For the noncensus years 1981–1989, rates are based on national estimates of the resident population as of July 1, rounded to thousands. Rounded population estimates for 10-year age groups are calculated by summing unrounded population estimates before rounding to thousands. Starting in 1991, rates are based on unrounded national population estimates. Rates for the Hispanic and non-Hispanic white populations in each year are based on unrounded state population estimates for states in the Hispanic reporting area. Death rates are expressed as the number of deaths per 100,000 resident population. The rate may be restricted to deaths in specific age, race, sex, or geographic groups or from specific causes of death (specific rate), or it may be related to the entire population (crude rate). (Also see Appendix I, Population Census and Population Estimates.)
  • Birth cohort infant mortality rates are based on the birth cohort linked birth and infant death files and are computed as the number of deaths under age 1 year to members of the birth cohort, divided by the number of live births, times 1,000. (Also see Appendix II, Birth cohort.)
  • Fetal mortality rate is the number of fetal deaths with stated or presumed gestation of 20 weeks or more, divided by the sum of live births plus fetal deaths, times 1,000.
  • Infant mortality rate is based on period files and is calculated by dividing the number of infant deaths during a calendar year by the number of live births reported in the same year. It is expressed as the number of infant deaths per 1,000 live births. Neonatal mortality rate is the number of deaths of infants under age 28 days per 1,000 live births. Postneonatal mortality rate is the number of infant deaths that occur between 28 days to under 1 year after birth, per 1,000 live births. (Also see Appendix II, Infant death.)
  • Late fetal mortality rate is the number of fetal deaths with stated or presumed gestation of 28 weeks or more, divided by the sum of live births plus late fetal deaths, times 1,000. (Also see Appendix II, Gestation.)
  • Perinatal mortality rates and ratios relate to the period surrounding the birth event. Rates and ratios are based on events reported in a calendar year. Although several different perinatal mortality definitions exist, the perinatal definition used inHealth, United States (and used most commonly for international comparisons) is the sum of late fetal deaths at 28 weeks of gestation or more plus infant deaths within 7 days of birth, divided by the sum of live births plus late fetal deaths, times 1,000. Perinatal mortality ratio is the sum of late fetal deaths plus infant deaths within 7 days of birth, divided by the number of live births, times 1,000.

■. Visit rate

  • Visit rate is a basic measure of service utilization for event-based data. Examples of events include physician office visits with drugs provided, or hospital discharges. In the visit rate calculation, the numerator is the number of estimated events, and the denominator is the corresponding U.S. population estimate for those who possibly could have had events during a given period of time. The interpretation is that for every person in the population there were, on average, x events. It does not mean that x of the population had events, because some persons in the population had no events while others had multiple events. The only exception is when an event can occur just once for a person (e.g., if an appendectomy is performed during a hospital stay). The visit rate is best used to compare utilization across various subgroups of interest, such as age or race groups or geographic regions.

Registered hospital

See Appendix II, Hospital.

Registration area

The United States has separate registration areas for birth, death, marriage, and divorce statistics. In general, registration areas correspond to states and include two separate registration areas for the District of Columbia (D.C.) and New York City. The term “reporting area” may be used interchangeably with the term “registration area.” All reporting areas have adopted laws that require registration of births and deaths and the reporting of fetal deaths. It is believed that more than 99% of births and deaths occurring in this country are registered.

The death registration area was established in 1900 with 10 states and D.C., and the birth registration area was established in 1915, also with 10 states and D.C. Beginning in 1933, all states were included in the birth and death registration areas. The specific states added year by year are shown in: Hetzel AM. History and organization of the vital statistics system. Hyattsville, MD: NCHS; 1997. Available from: http://www.cdc.gov/nchs/data/misc/usvss.pdf. Currently, Puerto Rico, the U.S. Virgin Islands, and Guam each constitute a separate registration area, although their data are not included in statistical tabulations of U.S. resident data. (Also see Appendix II, Reporting area.)

Relative standard error (RSE)

RSE is a measure of an estimate’s reliability. The RSE of an estimate is obtained by dividing the standard error of the estimate, SE(r), by the estimate itself, r. This quantity is expressed as a percentage of the estimate and is calculated as follows:

RSE=100 × [SE(r)/(r)]

Estimates with large RSEs are considered unreliable. In Health, United States, most statistics with large RSEs are preceded by an asterisk or are not presented. The criteria for evaluating RSEs is discussed in the footnotes accompanying each table.

Relative survival rate

The relative survival rate is the ratio of the observed survival rate for the patient group to the expected survival rate for persons in the general population similar to the patient group with respect to age, sex, race, and calendar year of observation. The 5-year relative survival rate is used to estimate the proportion of cancer patients potentially curable. Because more than one-half of all cancers occur in persons aged 65 and over, many of these individuals die of other causes with no evidence of recurrence of their cancer. Thus, because it is obtained by adjusting observed survival for the normal life expectancy of the general population of the same age, the relative survival rate is an estimate of the chance of surviving the effects of cancer.

Reporting area

In the National Vital Statistics System, the reporting area for such basic items on the birth and death certificates as age, race, and sex is based on data from residents of all 50 states in the United States, the District of Columbia, and New York City. The term “reporting area” may be used interchangeably with the term “registration area.” [Also see Appendix II, Registration area; and Appendix I, National Vital Statistics System (NVSS).]

Resident, health facility

In the Online Survey Certification and Reporting (OSCAR) database, all residents in certified facilities are counted on the day of certification inspection.

Resident population

See Appendix II, Population.

S

Serious psychological distress

The K6 mental health screening instrument is a measure of psychological distress associated with unspecified but potentially diagnosable mental illness that may result in a higher risk for disability and higher utilization of health services. In the National Health Interview Survey (NHIS), the K6 questions were asked of adults aged 18 and over. The K6 is designed to identify persons with serious psychological distress, using as few questions as possible. The six items included in the K6 are:

During the past 30 days, how often did you feel:

  • So sad that nothing could cheer you up?
  • Nervous?
  • Restless or fidgety?
  • Hopeless?
  • That everything was an effort?
  • Worthless?

Possible answers are “All of the time” (4 points), “Most of the time” (3 points), “Some of the time” (2 points), “A little of the time” (1 point), and “None of the time” (0 points).

To score the K6, the points are added together, yielding a possible total of 0–24 points. A threshold of 13 points or more is used to define serious psychological distress. Persons answering “Some of the time” to all six questions would not reach the threshold for serious psychological distress because to achieve a score of 13 they would need to answer “Most of the time” to at least one item. The version of the K6 used in NHIS provides 1-month prevalence rates because the reference period is the past 30 days. For more information, see: Kessler RC, Barker PR, Colpe LJ, Epstein JF, Gfroerer JC, Hiripi E, et al. Screening for serious mental illness in the general population. Arch Gen Psychiatry 2003;60(2):184–9. (Also see Appendix II, Basic actions difficulty.)

Short-stay hospital

See Appendix II, Hospital.

Skilled nursing facility

See Appendix II, Nursing home.

Special hospital

See Appendix II, Hospital.

Substance use

Substance use refers to the use of selected substances, including alcohol, tobacco products, drugs, inhalants, and other substances that can be consumed, inhaled, injected, or otherwise absorbed into the body with possible dependence and other detrimental effects. (Also see Appendix II, Illicit drug use.)

  • Monitoring the Future (MTF) Study—MTF collects information on the use of selected substances by using self-completed questionnaires in a school-based survey of secondary school students. MTF has tracked 12th graders’ illicit drug use and attitudes toward drugs since 1975. In 1991, 8th and 10th graders were added to the study. The survey includes questions on abuse of substances including (but not limited to) marijuana, inhalants, other illegal drugs, alcohol, cigarettes, and other tobacco products. [Also see Appendix I, Monitoring the Future (MTF) Study.]
  • National Survey on Drug Use & Health (NSDUH)—NSDUH conducts in-person, computer-assisted interviews of a sample of individuals aged 12 and over at their place of residence. For illicit drug use, alcohol use, and tobacco use, information is collected about use in the lifetime, past year, and past month. However, only estimates of use in the past month are presented inHealth, United States. For illicit drug use, respondents in NSDUH are asked about use of marijuana/hashish, cocaine (including crack), inhalants, hallucinogens, heroin, and prescription-type psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives) used nonmedically. A series of questions is asked about each substance: “Have you ever, even once, used [substance]?” “How long has it been since you last used [substance]?” Numerous probes and checks are included in the computer-assisted interview system. Nonprescription medications and legitimate use of prescription drugs under a doctor’s supervision are not included in the survey. Summary measures, such as current illicit drug use, are produced. [Also see Appendix II, Alcohol consumption; Cigarette smoking; Illicit drug use; and Appendix I, National Survey on Drug Use & Health (NSDUH).]

Suicidal ideation

Suicidal ideation means having thoughts of suicide or of taking action to end one’s own life. Suicidal ideation includes all thoughts of suicide, both when the thoughts include a plan to commit suicide and when they do not include a plan. Suicidal ideation is measured in the Youth Risk Behavior Survey by the following three questions: “During the past 12 months, did you ever seriously consider attempting suicide?”, “During the past 12 months, how many times did you actually attempt suicide?”, and “If you attempted suicide during the past 12 months, did any attempt result in an injury, poisoning, or overdose that had to be treated by a doctor or nurse?” For more information, see: http://www.cdc.gov/HealthyYouth/yrbs/index.htm.

Surgical specialty

See Appendix II, Physician specialty.

T

U

Uninsured

In the Current Population Survey (CPS), persons are considered uninsured if they do not have coverage through private health insurance, Medicare, Medicaid, Children’s Health Insurance Program, military or veterans coverage, another government program, a plan of someone outside the household, or other insurance. Persons with only Indian Health Service coverage are considered uninsured. In addition, if the respondent has missing Medicaid information but has income from certain low-income public programs, then Medicaid coverage is imputed. The questions on health insurance are administered in March and refer to the previous calendar year.

In the National Health Interview Survey (NHIS), the uninsured are persons who do not have coverage under private health insurance, Medicare, Medicaid, public assistance, a state-sponsored health plan, other government-sponsored programs, or a military health plan. Persons with only Indian Health Service coverage are considered uninsured. Estimates of the percentage of persons who are uninsured based on NHIS may differ slightly from those based on the March CPS because of differences in survey questions, recall period, and other aspects of survey methodology. Estimates for the uninsured are shown only for the population under age 65.

Survey respondents may be covered by health insurance at the time of interview but may have experienced one or more lapses in coverage during the year prior to interview. Starting with Health, United States, 2006, NHIS estimates for people with health insurance coverage for all 12 months prior to interview, for those who were uninsured for any period up to 12 months, and for those who were uninsured for more than 12 months were added as stub variables to selected tables. [Also see Appendix II, Health insurance coverage; and Appendix I, Current Population Survey (CPS).]

Urbanization

Urbanization is the degree of urban (city-like) character of a particular geographic area. Urbanization can be measured in a variety of ways. In Health, United States, the two measures used to categorize counties by urbanization level are the Office of Management and Budget’s (OMB) metropolitan statistical area (MSA) classification and the 2006 NCHS Urban–Rural Classification Scheme for Counties. For more information on the OMB classification of counties, see Appendix II, Metropolitan statistical area (MSA); Micropolitan statistical area.

The 2006 NCHS Urban–Rural Classification Scheme for Counties is a six-level classification scheme developed by NCHS to categorize the 3,141 U.S. counties and county equivalents based on their urban and rural characteristics. The classification scheme includes four metropolitan (or urban) categories and two nonmetropolitan (or rural) categories. The county classifications are based on the following information: (a) the December 2005 OMB definitions of metropolitan and micropolitan counties; (b) 2004 postcensal county and place population estimates; and (c) county-level data on selected settlement density, socioeconomic, and demographic variables from Census 2000. The six categories of the 2006 NCHS Urban–Rural Classification Scheme for Counties are large central metro (inner city counties of metropolitan areas of 1 million or more population), large fringe metro (suburban counties of metropolitan areas of 1 million or more population), medium metro (counties of metropolitan areas of 250,000– 999,999 population), small metro (counties of metropolitan areas with less than 250,000 population), nonmetropolitan micropolitan, and nonmetropolitan noncore. For more information on this classification scheme, see: http://www.cdc.gov/nchs/data_access/urban_rural.htm.

Usual source of care

Usual source of care was measured in the National Health Interview Survey (NHIS) in 1993 and 1994 by asking the respondent, “Is there a particular person or place that [person] usually goes to when [person] is sick or needs advice about [person’s] health?” In the 1995 and 1996 NHIS, the respondent was asked, “Is there one doctor, person, or place that [person] usually goes to when [person] is sick or needs advice about health?” Starting in 1997, the respondent was asked, “Is there a place that [person] usually goes when he/she is sick or you need advice about [his/her] health?” Persons who report the emergency department as their usual source of care are defined in Health, United States as having no usual source of care.

V

Vaccination

Vaccinations, or immunizations, work by stimulating the immune system—the natural disease-fighting system of the body. A healthy immune system is able to recognize invading bacteria and viruses and produce substances (antibodies) to destroy or disable these invaders. Vaccinations prepare the immune system to ward off a disease. In addition to the initial immunization process, the effectiveness of some immunizations can be improved by periodic repeat injections or “boosters.” Vaccines are among the most successful and cost-effective public health tools available for reducing morbidity and mortality from vaccine-preventable diseases. For a comprehensive list of vaccine-preventable diseases, see: http://www.cdc.gov/vaccines/vpd-vac/vpd-list.htm and http://www.cdc.gov/vaccines/spec-grps/default.htm.

The currently recommended childhood vaccination schedule includes vaccines that prevent infectious diseases including hepatitis A and B, diphtheria, tetanus toxoids, acellular pertussis (whooping cough), measles, mumps, rubella (German measles), polio, varicella (chicken pox), and some forms of meningitis (HIB), influenza, and pneumonia. In February 2006, a rotavirus vaccine (RotaTeq) was licensed for use in U.S. infants.

A vaccine that protects against the four types of human papillomavirus (HPV) that cause most cervical cancers and genital warts began to be marketed in 2006 and is now available for both females and males. The vaccine was recommended for 11- and 12 year-old girls and for girls and women aged 13–26 who have not yet been vaccinated or completed the vaccine series. In October 2011 HPV vaccination was recommended for males aged 11 and 12. Available from: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6050a3.htm.

Boosters (revaccination) of vaccinations received during childhood or adulthood are necessary for some vaccines. In addition to keeping current with the vaccines listed above, and annual influenza vaccination, some additional vaccinations are recommended for older adults, persons with specific health conditions, or health care workers who are likely to be exposed to infectious persons. Herpes zoster vaccination is recommended one time for adults aged 60 and over, and pneumococcal vaccination is recommended one time for adults aged 65 and over.

For a full discussion of recommended vaccination schedules by age and population, see CDC’s vaccination and immunization website at: http://www.cdc.gov/vaccines/schedules/index.html.

  • Influenza vaccination—In the National Health Interview Survey, questions concerning influenza vaccination were slightly different across the survey years. Respondents were asked, “During the past 12 months, have you had a flu shot? A flu shot is usually given in the fall and protects against influenza for the flu season.” Beginning in September 2003, respondents were asked about influenza vaccination by nasal spray (sometimes called by the brand name FluMist) during the past 12 months, in addition to the question regarding the flu shot. Starting with 2005 data, receipt of nasal spray or a flu shot was included in the calculation of influenza vaccination estimates. In 2010, additional questions were asked about the receipt of the H1N1 flu shot and spray, including month and year received. These H1N1 questions, and the original seasonal flu questions, were asked only in quarters 1 and 2 and the first several weeks of quarter 3. Beginning August 11, 2010, revised flu vaccination questions replaced all flu vaccination questions fielded earlier in 2010 and were also used in 2011. The revised questions reflect the introduction of a new combined flu vaccination that protects against both the seasonal and H1N1 strains. For more information regarding 2010 influenza questions, see: ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NHIS/2010/srvydesc.pdf.
    The prevalence of influenza vaccination during the past 12 months may differ from season-specific coverage, and estimates from different data sources may differ (additional estimates are available from: http://www.cdc.gov/flu/professionals/vaccination/vaccinecoverage.htm).

W

Y

Years of potential life lost (YPLL)

YPLL is a measure of premature mortality. Starting with Health, United States, 1996, YPLL has been presented for persons under age 75 because the average life expectancy in the United States is over 75 years. YPLL–75 is calculated using the following eight age groups: under 1, 1–14, 15–24, 25–34, 35–44, 45–54, 55–64, and 65–74. The number of deaths for each age group is multiplied by years of life lost, calculated as the difference between age 75 years and the midpoint of the age group. For the eight age groups, the midpoints are 0.5, 7.5, 19.5, 29.5, 39.5, 49.5, 59.5, and 69.5 years, respectively. For example, the death of a person aged 15–24 counts as 55.5 years of life lost. Years of potential life lost is derived by summing years of life lost over all age groups. In Health, United States, 1995 and earlier editions, YPLL was presented for persons under age 65. For more information, see: CDC. Premature mortality in the United States: Public health issues in the use of years of potential life lost. MMWR 1986;35(SS–02):1S–11S. Available from: http://www.cdc.gov/mmwr/preview/mmwrhtml/00001773.htm.

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