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National Center for Health Statistics (US) . Health, United States, 2009: With Special Feature on Medical Technology. Hyattsville (MD): National Center for Health Statistics (US); 2010 Jan.

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Health, United States, 2009: With Special Feature on Medical Technology.

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Technical Notes

Data Sources and Comparability

Data for the Chartbook come from many surveys and data systems and cover a broad range of years. Detailed descriptions of data sources are provided in Appendix I.

Data Presentation

Many measures in the Chartbook section are shown for people in specific age groups because of the strong effect age has on most health outcomes. Some estimates are age-adjusted using the age distribution of the 2000 standard population, and this is noted in the data tables that accompany each figure (see Appendix II, Age adjustment). Age-adjusted rates are computed to eliminate differences in observed rates that result from age differences in population composition. For some figures, data years are combined to increase sample size and reliability of the estimates. Some charts present time trends and others focus on differences in estimates among population subgroups for the most recent time point available.

Graphic Presentation

Most trends are shown on a linear scale to emphasize absolute differences over time. The linear scale is the scale most frequently used and recognized, and it emphasizes the absolute changes between data points over time (1). The time trends for overall mortality measures are shown on a logarithmic (log) scale to emphasize the rate of change and to enable measures with large differences in magnitude to be shown on the same chart. Log scales emphasize the relative or percentage change between data points. Readers are cautioned that one potential disadvantage to the log scale is that the absolute magnitude of changes may appear smaller than the untransformed statistics would indicate (2). When interpreting data on a log scale, the following points should be kept in mind:

  • A sloping straight line indicates a constant rate (not amount) of increase or decrease in the values.
  • A horizontal line indicates no change.
  • The slope of the line indicates the rate of increase or decrease.
  • Parallel lines, regardless of their magnitude, depict similar rates of change (1).

Tabular Presentation

Following the Technical Notes are data tables that present the data points graphed in each figure. Some data tables contain additional data that were not graphed because of space considerations. Standard errors for data points are provided for many measures. Additional information clarifying and qualifying the data are included in table notes and in Appendixes I and II where indicated.

Survey Questions and Coding

Additional information on the data used in the Chartbook and Special Feature, including the exact wording of questions and coding schemes, is detailed below.

National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS)

Figure 25: The trend shown in this figure should be interpreted with caution because the type of information available on imaging scans differed by health care setting and years shown.

For physician office visits and hospital outpatient department visits: In 1996–2000, the questionnaire forms contained check boxes for MRI or CT scans ordered or provided during the visit. There was no check box for PET scans, but there was a field for other procedures ordered or performed during the visit. In 2001–2004, the questionnaire forms did not include check boxes for MRI, CT, or PET scans; thus, these data years are not shown in Figure 25. For 2005 and 2006, the questionnaire forms contained a check box for MRI, CT, or PET scans and fields for other types of procedures ordered or performed. In 2005–2006, the fields for other types of procedures ordered or performed during the visit were reviewed by NCHS during the file editing process and, if they contained the following set of procedure codes, the check box for MRI, CT, or PET scans was edited by NCHS to include information from the other procedure fields if it was not already present. The International Classification of Diseases, ninth revision, Clinical Modification (ICD–9–CM) procedure codes used by NCHS to identify advanced imaging scans included: 00.31, 00.32, 87.03, 87.41, 87.71, 88.01, 88.38, 92.01–92.05, 92.09, 92.11–92.19, 95.16, and 88.91–88.97. To make the analysis for Figure 25 more comparable over time, the write-in fields from the 1996–2000 questionnaires were searched for the above list of procedures and included in the estimates. Thus, estimates published in this analysis for physician offices and hospital outpatient department imaging visits may differ slightly from those previously published elsewhere that did not include data on advanced imaging scans in the write-in fields.

In 1996–2006, the NHAMCS emergency department questionnaire included check boxes for MRI or CT scans ordered or provided during the visit. There is no check box for PET scans because these scans are rarely ordered or performed in an emergency department. There were no write-in fields for other procedures on this questionnaire.

National Health and Nutrition Examination Survey (NHANES)

Figure 8: In 2005 and 2006, the sleep questionnaire was administered to persons 16 years of age and over. Proxies were permitted to answer the sleep questions, but typically people answer these questions for themselves. Persons who responded “often“ (5–15 times in the past month) or “almost always“ (16–30 times in the past month) to any of the following three questions were considered to have had trouble sleeping through the night in the past month. “In the past month, how often did you/[sample person] have trouble falling asleep?“ “In the past month, how often did you/[sample person] wake up during the night and have trouble getting back to sleep?“ “In the past month, how often did you/[sample person] wake up too early in the morning and were unable to get back to sleep?“

Respondents were also asked: “In the past month, how often did you/[sample person] take sleeping pills or other medication to help you/[sample person] sleep?“ Persons who replied “often“ (5–15 times in the past month) or “almost always“ (16–30 times in the past month) were considered as often or almost always taking sleeping pills in the past month.

Figure 12: Depression is a self-reported assessment using the Patient Health Questionnaire (PHQ–9), a nine-item screening instrument that asks questions about the frequency of symptoms of depression over the past 2 weeks. The survey questions were:

Over the last 2 weeks, how often have you been bothered by the following problems:

  • Little interest or pleasure in doing things?
  • Feeling down, depressed, or hopeless?
  • Trouble falling or staying asleep, or sleeping too much?
  • Feeling tired or having little energy?
  • Poor appetite or overeating?
  • Feeling bad about yourself—or that you are a failure or have let yourself or your family down?
  • Trouble concentrating on things, such as reading the newspaper or watching TV?
  • Moving or speaking so slowly that other people could have noticed? Or the opposite—being so fidgety or restless that you have been moving around a lot more than usual?
  • Thoughts that you would be better off dead or of hurting yourself in some way?

Respondents selected a response category based on the frequency of their symptoms over the last 2 weeks. The response categories were given a score from 0 to 3. A total score was calculated ranging from 0 to 27. Depression was defined as a PHQ–9 score of 10 or higher.

Not at all0
Several days1
More than half the days2
Nearly every day3

For more information, see the NHANES survey documentation for this screener, available from:

Limitations to the prevalence estimates include the possibility that severely depressed persons disproportionately chose not to participate in the survey or health examination, which included administration of the PHQ–9. Therefore, the prevalence estimates based on these data may slightly underestimate the actual prevalence of depression. In addition, people who were being successfully treated for depression would not be identified as depressed by the PHQ–9. For more information see: Pratt LA, Brody DJ. Depression in the United States household population, 2005–2006. NCHS data brief; no 7. Hyattsville, MD: NCHS; 2008. Available from:

Figure 34: The questionnaire administered to all participants included a question on whether they had taken a prescription drug in the past month. Those who answered “yes“ were asked to show the interviewer the medication containers for all the prescriptions. For each drug 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 drug. More information on prescription drug data collection and coding in NHANES is available from: Also see Appendix I, National Health and Nutrition Examination Survey. Respondents reporting use of a prescription drug containing any of the following ingredients: atorvastatin, cerivastatin, fluvastatin, lovastatin, pravastatin, simvastatin were classified as taking a statin drug.

Antidiabetic drugs were identified using the following drug categories: for 1988–1994 data, drugs in NDC class 1036–blood glucose regulators, were included; for 2003–2006 data, drugs in the Multum Lexicon Therapeutic Classification Scheme, second category, 99–antidiabetic agents, were included.

U. S. Department of Labor, Bureau of Labor Statistics (BLS), Survey of Occupational Injuries and Illnesses (SOII)

Figure 11: In the SOII, an occupational injury is any injury, such as a cut, fracture, sprain, or amputation, that results from a work-related event or from a single instantaneous exposure in the work environment. An occupational illness is any abnormal condition or disorder other than one resulting from an occupational injury, caused by exposure to factors associated with employment. It includes acute and chronic illnesses or diseases that may be caused by inhalation, absorption, ingestion, or direct contact. To determine whether an injury or illness is recordable, employers use a decision framework developed by the Occupational Safety and Health Administration (OSHA). For more information on this framework, see: The SOII data represent persons employed in private industry establishments in the United States. The survey excludes the self-employed, farms with fewer than 11 employees, private households, federal government agencies, and state and local government agencies. For more information, see Appendix I, Survey of Occupational Injuries and Illnesses, and see: Occupational safety and health statistics. In: BLS handbook of methods [online]. U.S. Bureau of Labor Statistics. 2008. Available from:

Three major data collection changes—in 1992, 1995, and 2002—affect the interpretation of SOII data. In 1992, the survey was redesigned, and detailed characteristics about workplace injury and illness cases began to be collected. In addition, a separate program to track workplace fatalities—the Census of Fatal Occupational Injuries—was introduced. Starting with 1995 data, employers were required to submit annual summaries of occupational injuries and illnesses.

Effective January 1, 2002, OSHA revised its requirement and forms for recording occupational injuries and illnesses. Prior to 2002, injury and illness cases involved days away from work, days of restricted work activity, or both (lost workday cases). Starting in 2002, injury and illness cases may involve days away from work, job transfer, or restricted work activity. Restriction may involve shortened hours, a temporary job change, or temporary restrictions on certain duties (for example, no heavy lifting) of a worker’s regular job. Other changes include increasing the types of events exempt from reporting. See: for details about the revised recordkeeping requirements.

Because of the revised recordkeeping rule, the estimates from the 2002 survey and beyond are not comparable with those from previous years. According to a BLS analysis, changes to the program prior to 2002 affected the type and amount of data available but did not change the basic definition of recordable cases of injuries and illnesses. Thus, data on the number and rate of occupational injuries and illnesses are consistent from 1972 through 2001. For more information, see: Wiatrowski WJ. Occupational injury and illnesses: New recordkeeping requirements. Mon Labor Rev 2004;127(12):10–24. Available from:

U.S. Department of Veterans Affairs

Figure 3: Veterans data include information about living veterans from the 50 states, the District of Columbia, Puerto Rico, and outlying U.S. areas. Data only include persons who served on active duty. Service-connected disability (SCD) data used for this analysis are from the U.S. Census Bureau, based on data from the Department of Veterans Affairs. SCD status data for 1970 and 1980 are from tables 618 and 620 of the 1981 Statistical Abstract of the United States. Disability data for 1990 and 2000 are from table 506 of the 2009 Statistical Abstract of the United States. SCD data for 2007 are based on unpublished data from the Department of Veterans Affairs. SCD status is based on the number of living veterans qualified as having an SCD incurred or aggravated while on active duty and receiving financial compensation for that SCD. Data are as of September 30 for 1980 to present. Data are as of June 30 for 1970. Percentages are based on numbers in thousands. The total number of living veterans for 2007 is from the Veterans Administration. Veterans are classified in their earliest period of service. For example, a living veteran who served in the Vietnam era, the Korean conflict, and World War II, is classified as a World War II veteran for this analysis. Data do not include living veterans who served prior to World War II. It is estimated that there are only about 300 living veterans from World War I. Gulf War service is from August 2, 1990, to present and does not reflect deployment or service location.

The Statistical Abstract of the United States is available from: Veterans Administration data are available from:

Healthcare Cost & Utilization Project, Nationwide Inpatient Sample

Figure 36: The costs shown are for the entire hospital stay, not just the cost of performing the principal procedure. Costs were derived from total hospital charges (the amount the hospital billed for the hospital stay) by using cost-to-charge ratios based on hospital accounting reports from the Centers for Medicare & Medicaid Services (CMS). For each hospital, a hospital-wide cost-to-charge ratio was used to transform charges into costs. Costs will tend to reflect the actual costs to produce hospital services, whereas charges represent what the hospital billed for the care. Hospital costs do not include professional billing (physician fees). Hospital costs were adjusted to 2006 dollars by using the gross domestic product price index.

Principal procedures were identified by using Clinical Classifications Software (CCS), which combines relevant International Classification of Diseases, ninth revision, Clinical Modification (ICD–9–CM) procedure codes into meaningful groups. The principal procedure is the procedure that was performed for definitive treatment, rather than one performed for diagnostic or exploratory purposes or the procedure that was necessary to take care of a complication. If two procedures appear to meet this definition, the one most related to the principal diagnosis is selected as the principal procedure. CCS codes were as follows: 216, respiratory intubation and mechanical ventilation; 45, percutaneous transluminal coronary angioplasty (PTCA); 44, coronary artery bypass graft; 48, cardiac pacemaker, cardioverter, defibrillator; 158, spinal fusion; and 152, knee arthroplasty.


Page RM, Cole GE, Timmreck TC. Basic epidemiological methods and biostatistics: A practical guidebook. Sudbury, MA: Jones & Bartlett; 1995.
Jekel JF, Elmore JG, Katz DL. Epidemiology biostatistics and preventive medicine. Philadelphia, PA: W.B. Saunders; 1996.
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