Table 19Summary of studies of the relationship between health literacy and the outcome of health care related skills (KQ 1b)

Authors, Year, Study Design, Analysis Sample Size, QualityPopulation and Setting, Health Literacy LevelVariables used in Multivariate AnalysisOutcome Measure

Results By Health Literacy Level
Differences in Results Between Health Literacy Levels
Kripalani et al., 2006123

Cross-sectional

N = 152

Good
Clinic population with coronary heart disease in Atlanta, GA

REALM
Inadequate: 52%
Marginal: 29%
Adequate: 20%
Age
Education
Cognitive functioning
DRUGS: Requiring observed completion of 4 tasks:
  1. Identify appropriate medication
  2. Open container
  3. Select correct dose
  4. Report appropriate timing of doses.
Mean score:
Inadequate: 92.1
Marginal: 96.3
Adequate: 97.7
Difference across groups in overall DRUGS score (unadjusted): P = 0.001

Inadequate more likely than adequate to not be able to identify all medications (adjusted): OR, 12.00; 95% CI, 2.57-56.08

No difference between marginal and adequate in ability to identify all medications (adjusted): OR, 4.75; 95% CI, 0.95-23.75
Raehl et al., 2006124

Cross-sectional

N = 57

Fair
Seniors in Amarillo, Texas

REALM mean: 55.4
Age
Number of over-the-counter drugs
Owned a car in last 10 years
Received food assistance in last 10 years
MedTake Test: ability to open and take own medications while observed by pharmacist

MedTake Test outcomes: NR
A higher MedTake Test score was associated with a higher REALM score (adjusted): P < 0.01
Yin et al., 2007125

Cross-sectional

N = 292

Fair
Parents/caregivers of children at an Emergency Department in New York City

TOFHLA
Inadequate: 10%
Marginal: 16%
Adequate: 74%
Experience of ever receiving a dosing instrument in a health care setting
Child's age
Child has regular health care provider
Confounders with health literacy: Caregiver's education, country of origin, language, socio-economic status
Self-reported use of nonstandardized dosing instrument

Inadequate/Marginal: 35%
Adequate: 19%
No difference in use of dosing instrument between health literacy groups (adjusted for all control variables): OR, 1.5; 95% CI, 0.8-2.8

Marginal/inadequate greater use than adequate (adjusted for control variables except for confounders with HL): OR, 1.9; 95% CI, 1.0-3.5
Estrada et al., 2004126

Prospective cohort

N = 143

Fair
Adults greater than 50 years old on warfarin ≥ 1 month in 2 anticoagulation management units

REALM
≤ 3rd: 11%
4th-6th: 15%
7th-8th: 26%
>8th: 48%
AgeWarfarin control measured through INR variability: NR

Optimal intensity of anticoagulation (time in range): NR
No difference by HL level in INR variability (adjusted): P = 0.06

No difference by HL time INR in therapeutic range (adjusted): P = 0.71
Davis et al., 200675
(Analysis 1)

Wolf et al., 200776
(Analysis 2)

Cross-sectional

N = 395

Fair
Adults in primary care clinics in Shreveport, LA; Jackson, MI; and Chicago, IL

REALM
Inadequate: 19%
Marginal: 29%
Adequate: 52%
Analysis 1
Age
Sex
Race
Education
Number of medications currently taken daily
Site

Analysis 2
None
Misunderstood one or more prescription label instructions:

Inadequate: 63%
Marginal: 51%
Adequate: 38%

Correct demonstration of number of pills:

Inadequate: 35%
Marginal: 63%
Adequate: 80%
Analysis 1

Greater misunderstanding in inadequate compared to adequate group (adjusted): RR, 2.32; 95% CI, 1.26-4.28

Greater misunderstanding in marginal compared to adequate group (adjusted): RR, 1.94; 95% CI, 1.14-3.2

Greater demonstration of pills in adequate compared to inadequate group (adjusted): RR, 3.02; 95% CI, 1.70-4.89

No difference between marginal and adequate groups in demonstration of pills: RR = NS, data NR

Analysis 2

Difference across literacy groups in correctly interpreting primary label (unadjusted)

Amoxicillin: P < 0.001
Trimethoprim: P < 0.001
Guaifenesin: P < 0.001
Felodipine: P = 0.03
Furosemide: P = 0.09

Difference across literacy groups in correctly attending to auxiliary label (unadjusted)

Amoxicillin: P = 0.13
Trimethoprim: P = 0.14
Guaifenesin: P < 0.001
Felodipine: P = 0.11
Furosemide: P = 0.01
Rothman et al., 20069

Cross-sectional

N = 200

Fair
Adults in primary care clinic

REALM
< HS: 23%
> HS: 77%
Age
Gender
Race/ethnicity
Income
Education
Insurance status
Presence of chronic disease
Status of being on a specific diet
Label reading frequency
Understanding nutrition labels measured through Nutrition Label Survey

Nutritional Label Survey score mean (SD):
< HS: 51 (16)
> HS: 75 (19)
Greater understanding of nutrition labels in higher HL group (adjusted): P < 0.001
Bailey et al, 200977 (Companions: Davis et al., 200675, Wolf et al., 200776)

Cross-sectional

N = 373

Fair
Adults in Shreveport, La; Chicago, IL, and Jackson, Michigan

REALM:
Low: ≤ 6th grade: 20%
Marginal: 7th-8th
grade: 29%
Adequate: ≥ 9th
grade: 51%
Race
Age
Sex
Education
Misinterpretation of medication label instructions:

Low: 43%
Marginal: 34%
Adequate: 18%
In comparison to group with adequate HL (adjusted):

Greater probability of marginal group misinterpreting medication instructions: AOR, 2.20; 95% CI, 1.19-3.97

Greater probability of low group misinterpreting medication instructions: AOR, 2.90; 95% CI, 1.41-6.00
Yin et al, 2010127

Cross-sectional

N = 302

Good
English- and Spanish-speaking parents whose child received care at public pediatric clinic in NY

Newest Vital Sign

High likelihood of limited literacy: 40%
Possible limited literacy: 38%
Adequate literacy: 22%
Parent's age
Relationship to child
Marital status
Language
Ethnicity
US birth
SES
Presence of a child in the house <8 years old
Presence of child in the household with a chronic medical problem
Accuracy in measuring a dose of medicine using 6 different dosing instruments: NRIn comparison to group with adequate HL, the odds of making any dosing error (>20% deviation) was greater in those with a high likelihood of limited HL: AOR, 1.7; 95% CI, 1.1-2.8 and in those with possible limited HL: AOR, 1.6; 95% CI, 1.02-2.6

In comparison to group with adequate HL, odds of making a large dosing error (>40% deviation) was greater in those with a high likelihood of limited HL: AOR, 2.3; 95% CI, 1.2-4.6 but no difference in those with possible limited HL: AOR, 1.9; 95% CI, 0.95-3.7
LeVine et al., 2004128

Cross-sectional

N = 167

Fair
Mothers of kindergarten age children in urban and rural Nepal

Literacy measured as continuous, composite score of reading comprehension and noun definition (in Nepalese)

Levels NR
Maternal schooling
Childhood socioeconomic status
Age
Current socioeconomic status
Husband's schooling
Urban/rural
Comprehension of radio health messages: NR

Comprehension of visual print health message: NR

Ability to give an organized health-related narrative: NR
Higher literacy level associated with greater probability of giving an organized health narrative (adjusted): P < 0.05
Paasche-Orlow et al., 200579

Cross-sectional

N = 73

Fair
Inpatient adults hospitalized for severe asthma at 2 inner city hospitals

s-TOFHLA
Inadequate: 22%
Adequate: 78%
Age
Sex
Ethnicity
Education
Income
History of near fatal asthma
Asthma hospitalization in prior 12 months
Having a physician for asthma care
Prior emergency department visit for asthma last 12 months (subset of confounders used in final model specification NR)
Mastery of metered dose inhaler technique

Inadequate: 32%
Adequate: 63%
Poorer probability of mastery of metered dose inhaler in inadequate than adequate group (adjusted): OR, 0.29; 95% CI, 0.08-1.00; P = 0.03
Waldrop-Valverde et al, 200947

Cross-sectional

N = 155

Fair
Adults with HIV in HIV clinics or AIDS drug assistance programs in Miami, FL

TOFHLA (% correct)
Men: 78%
Women: 73%
Gender
Education
Time since HIV diagnosis
Numeracy
Medication Management Test (MMT), a mock trial of medication-taking skills (interpretation of medication labels and a medication insert, counting a week's supply of medication and placing them in an organizer, and determining missed doses and refills)

HL data NR
Higher HL related to better MMT score (adjusted):
P < 0.05

AIDS=acquired immune deficiency syndrome; AOR=adjusted odds ratio; BMI=Body Mass Index; CI=confidence interval; DRUGS=Drug Regimen Unassisted Grading Scale; FL=Florida; GA=Georgia; HIV=Human immunodeficiency virus; HL=health literacy; HS=high school; IL=Illinois; INR=International Normalized Ratio; LA=Louisiana; MI=Michigan; N=number; NR=not reported; NY=New York; OR=odds ratio; REALM=rapid estimate of adult literacy in medicine; RR=risk ratio; SD=standard deviation; S-TOFHLA=Short Test of Functional Health Literacy in Adults; SES=socio-economic status; TOFHLA=Test of Functional Health Literacy in Adults; US=United States.

From: Results: Relationship of Health Literacy to Outcomes and Disparities

Cover of Health Literacy Interventions and Outcomes: An Updated Systematic Review
Health Literacy Interventions and Outcomes: An Updated Systematic Review.
Evidence Reports/Technology Assessments, No. 199.
Berkman ND, Sheridan SL, Donahue KE, et al.

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