Conclusions

Nancy D Berkman; Stacey L Sheridan; Katrina E Donahue; David J Halpern; Anthony Viera; Karen Crotty; Audrey Holland; Michelle Brasure; Kathleen N Lohr; Elizabeth Harden; Elizabeth Tant; Ina Wallace; Meera Viswanathan

This publication is provided for historical reference only and the information may be out of date.

Conclusions

Our systematic review update confirms that lower health literacy as measured by poorer reading skills is associated with a range of adverse health outcomes. Evidence is beginning to emerge concerning the relationship between poorer numeracy skills and health outcomes but the evidence is still too weak to be confident of an association. We found no evidence evaluating oral (verbal) health literacy and health outcomes.

Rigorous, well-designed studies of interventions to mitigate the effects of low health literacy have been conducted since our earlier review. Future studies isolating one measurable and replicable component of an intervention will, however, be particularly helpful in building this body of evidence. Many studies have now been conducted with a variety of clinic populations. Future research could enhance our confidence in the more universal applicability of results by including more broadly based and representative samples.

Table 62. Health outcome study results (KQ1): summary and comparison of 2004 and 2010 systematic reviews

Table 63. Numeracy outcome study results (KQ 1): summary of 2010 systematic review

Table 64. Results of intervention studies with single design strategies (KQ 2): summary and comparison of 2004 and 2010 systematic reviews

Table 65. Results of interventions with multiple design strategies: summary and comparison of 2004 and 2010 systematic reviews

Publication Details

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Agency for Healthcare Research and Quality (US), Rockville (MD)

NLM Citation

Berkman ND, Sheridan SL, Donahue KE, et al. Health Literacy Interventions and Outcomes: An Updated Systematic Review. Rockville (MD): Agency for Healthcare Research and Quality (US); 2011 Mar. (Evidence Reports/Technology Assessments, No. 199.) Conclusions.

Table 62Health outcome study results (KQ1): summary and comparison of 2004 and 2010 systematic reviews

Outcome	Study design	Number of articles: 2004 (Number controlling for confounding)	Number of articles: 2010 (Number controlling for confounding)	Low Health Literacy Related Results: 2004	Low Health Literacy Related Results: 2010	Strength of Evidence: 2010
Hospitalization	Cohort	2 (2)	4 (3)	Increase	Increase	Moderate
Hospitalization	Cross-sectional	0	2 (2)	Increase	Increase	Moderate

Emergency care visits	Cohort	0	4 (3)	NA: no studies	Increase	Moderate
Emergency care visits	Cross-sectional	0	3 (3)	NA: no studies	Increase	Moderate

Colon screening	Cross-sectional	0	5(5)	NA: no studies	Decrease	Insufficient

Pap tests	Cross-sectional	1(1)	3(3)	Decrease	Decrease	Low

Mammogram	Cross-sectional	1(1)	4(4)	Decrease	Decrease	Moderate

STI (testing)	Cross-sectional	1(1)	1(1)	Increase	Increase	Low

Immunization: Influenza	Cohort	0	1(1)	Decrease	Decrease	Moderate
Immunization: Influenza	Cross-sectional	1(1)	3(3)	Decrease	Decrease	Moderate

Immunization: Pneumococcal	Cohort	0	1(1)	Decrease	Mixed	Insufficient
Immunization: Pneumococcal	Cross-sectional	1(1)	1(1)	Decrease	Mixed	Insufficient

Access to care	Cohort	0	4(4)	No difference	Mixed	Insufficient
Access to care	Cross-sectional	1(1)	5(5)	No difference	Mixed	Insufficient

Access to insurance	Cross-sectional	0	1(1)	NA: no studies	Decrease	Low

Knowledge	Cohort	1 (0)	NA	Decrease	NA: analysis not repeated	Not re-evaluated
Knowledge	Cross-sectional	9 (7)	NA	Decrease	NA: analysis not repeated	Not re-evaluated

Adherence	Cohort	2 (0)	6 (6)	Mixed	Mixed	Insufficient
Adherence	Cross-sectional	2 (1)	9 (9)	Mixed	Mixed	Insufficient

Self-efficacy	Cross-sectional	0	5 (4)	NA: no studies	Mixed	Insufficient

Smoking	Cross-sectional	3 (1)	2 (2)	Mixed	Mixed	Insufficient

Alcohol and drug use	Cross-sectional	1 (1)	2 (2)	No difference	Mixed	Insufficient

Healthy lifestyle (physical activity, eating habits, and seat belt use)	Cross-sectional	0	3 (3-for some outcomes)	NA: no studies	Mixed	Insufficient

Obesity and weight	Cohort	0	1 (0)	NA: no studies	Mixed	Insufficient
Obesity and weight	Cross-sectional	0	4 (1)	NA: no studies	Mixed	Insufficient

Review of prescription information	Cross-sectional	0	1 (1)	NA: no studies	Decrease	Low

HIV risk and sexual behavior	Cohort	0	1 (1)	NA: no studies	Mixed	Insufficient
HIV risk and sexual behavior	Cross-sectional	0	1 (1)	NA: no studies	Mixed	Insufficient

Taking medications appropriately	Cohort	0	1 (1)	NA: no studies	Decrease	Moderate
Taking medications appropriately	Cross-sectional	0	4 (4)	NA: no studies	Decrease	Moderate

Interpreting labels and health messages	Cross-sectional	0	5 (4)	NA: no studies	Decrease	Moderate

Asthma self care	Cross-sectional	1 (1)	1 (1)	Decrease	Decrease	Low

Mental health symptomatology	Cohort	1 (0)	2 (1)	Decrease	Greater in 8 studies	Low
Mental health symptomatology	Cross-sectional	4 (2)	8 (4)	Decrease	Greater in 8 studies	Low

Chronic disease	Cohort	1 (1)	2 (0)	No difference	Mixed	Insufficient
Chronic disease	Cross-sectional	1 (1)	5 (3)	No difference	Mixed	Insufficient

HIV severity and symptoms	Cohort		1 (1)	Mixed	No difference in 4 studies	Low
HIV severity and symptoms	Cross-sectional	3 (0)	4 (3)	Mixed	No difference in 4 studies	Low

Asthma severity and control	Cross-sectional	0	2 (1)	NA: no studies	Mixed	Insufficient

Diabetes control and related symptoms	Cross-sectional	3 (2)	6 (5)	Mixed	Mixed	Insufficient

Hypertension control	Cross-sectional	1 (1)	2 (2)	No difference	Mixed	Insufficient

Prostate cancer control	Cross-sectional	1 (1)	1 (1)	No difference	Decrease	Low

Health status: all adults	Cross-sectional	2 (2)	1 (1)	Decrease	No difference	Low

Health status and QoL seniors: Mental & physical functioning: seniors	Cohort	0	1 (1)	Decrease	Decrease	Moderate
	Cross-sectional	1 (0)	5 (4)	Decrease	Decrease	Moderate
	Cohort		3 (2)	NA: no studies	Mixed	Insufficient
	Cross-sectional	0	2 (2)	NA: no studies	Mixed	Insufficient

Health status and QoL: specific diseases	Cross-sectional	2 (0)	5 (5)	No difference	Mixed	Insufficient

Mortality: seniors	Cohort	0	3 (3)	NA: no studies	Greater	High

Costs	Cohort	1 (1)	2(2)	No difference	Mixed	Insufficient

Disparities	Cohort	0	1 (1)	HL mediates racial disparity in 1 study	HL partially mediates: racial disparities in some outcomes, no differences in Hispanic ethnicity, sex differences for 1 outcome	Race: Low Hispanic ethnicity: Low Sex: Low
Disparities	Cross-sectional	1 (1)	5 (5)	HL mediates racial disparity in 1 study		Race: Low Hispanic ethnicity: Low Sex: Low

: HL=health literacy; NA=not applicable; QoL=quality of life; STI=sexually transmitted infection

Table 63Numeracy outcome study results (KQ 1): summary of 2010 systematic review^*

Outcome	Study design	Number of articles: 2010 (Number controlling for confounding)	Low Numeracy Literacy Related Results: 2010	Strength of Evidence: 2010
Use of health care services	Cross-sectional	1(1)	No effect	Low

Accuracy of risk perception	Cross-sectional	5(3)	Mixed	Insufficient

Knowledge	Cross-sectional	4(3)	Mixed	Insufficient

Self-efficacy	Cross-sectional	1(0)	Decrease	Insufficient

Behavior	Cross-sectional	1(0)	No effect	Insufficient

Skills	Cohort	1(1)	Taking medication (n=4): Mixed Interpreting health information (n=2): Decrease	Taking medication: Insufficient Interpreting health information: Low
Skills	Cross-sectional	5(4)

Disease prevalence and severity	Cross-sectional	3(2)	Mixed	Insufficient

Disparities	Cross-sectional	2(2)	Numeracy partially mediates the relationship between race and 1 outcome and between gender and 1 outcome	Low

*: Numeracy studies were not included in the 2004 review

: n=number

Table 64Results of intervention studies with single design strategies (KQ 2): summary and comparison of 2004 and 2010 systematic reviews ^*

Design Strategy	Study design	Number of articles (Number stratifying results by HL level): 2004	Number of articles (Number stratifying results by HL level): 2010	Low Health Literacy Related Results: 2004	Low Health Literacy Related Results: 2010	Strength of Evidence: 2010

Alternative Document Design	RCT	1(1)	2(2)	Increased	Increased	Low

Alternative Numerical Presentation	RCT	0	3(3)	NA	Increased	Low

Additive and Alternative Pictorial Representation	RCT	0	8(5)	NA	Mixed	Insufficient
Additive and Alternative Pictorial Representation	Quasi (pre/post)	0	8(5)	NA	Mixed	Insufficient

Alternative Media	RCT	1(1)	4(3)	Mixed	Mixed	Insufficient
Alternative Media	NRCT	2(1)	4(3)	Mixed	Mixed	Insufficient

Alternative Readability and Document Design	RCT	2(0)	6(3)	Mixed	Mixed	Insufficient
	Quasi (post)	0	1(1)
	NRCT	3(3)	1(1)

Physician Notification of HL Level	cRCT	0	1(1)	NA	No effect (patient outcomes)	Low

*: Studies in 2004 report reorganized into 2010 framework (e.g. single vs. multiple design strategy interventions) for reporting cRCT=cluster randomized controlled trial; HL=health literacy; NA=not applicable; NRCT=non-randomized controlled trial; quasi=quasi-experimental study; RCT=randomized controlled trial

Table 65Results of interventions with multiple design strategies: summary and comparison of 2004 and 2010 systematic reviews^*

Outcome	Study design	Number of articles (Number stratifying results by HL level): 2004	Number of articles (Number stratifying results by HL level): 2010	Low Health Literacy Related Results: 2004	Low Health Literacy Related Results: 2010	Strength of Evidence: 2010

Knowledge	RCT	2(1)	3(1)	Mixed	Mixed	Insufficient
	Quasi (pre/post)	1(0)	5(2)
	Quasi (post)	1(0)	2(2)
	NRCT	1(0)	0

Self-efficacy	RCT	0	4(1)	NA	Mixed	Insufficient
	Quasi (pre/post)	0	4(0)
	Quasi (post)	0	1(0)

Behavioral Intent		0	0	NA	NA	NA

Skill	RCT	0	1(1)	Mixed	Increased	Insufficient^*
	Quasi (pre/post)	1(1)	0
	NRCT	1(0)	0

Behavior	RCT	2 (0)	2(0)	Nutrition interventions: Mixed	Self-management interventions: Increased	Self-management interventions: Moderate Nutrition interventions: Insufficient
	Quasi (pre/post)	0	1(1)
	NRCT	1	0

Adherence	RCT	0	2(0)	No effect	Mixed	Insufficient
	Quasi (pre/post)	0	1(1)
	Quasi (post)	0	1(1)
	NRCT	1 (0)	0

Disease Prevalence and Severity	RCT	3(0)	4(2)	No effect	Self-management: Insufficient Disease management: Moderate Adult basic and Lit. Education: Low	Self-management: Insufficient Disease management: Moderate Adult Basic and Education: Low
Disease Prevalence and Severity	Quasi	0	3(3)	No effect

Quality of Life	RCT	0	4(0)	NA	Mixed	Insufficient

Preventive service use	RCT	0	1(0)	NA	Increased	Moderate
Preventive service use	cRCT	0	1(1)	NA	Increased	Moderate

Emergency Room Visits	RCT	0	1(0)	NA	Reduced	Moderate
Emergency Room Visits	Quasi (pre/post)	0	1(1)	NA	Reduced	Moderate

Hospitalization	RCT	0	2(1)	NA	Reduced	Moderate
Hospitalization	Quasi (pre/post)	0	1(1)	NA	Reduced	Moderate

Cost	RCT	0	2(0)	NA	Mixed	Insufficient

Disparities		0	0	NA	NA	Insufficient

*: Studies in 2004 report reorganized into 2010 framework (e.g. single vs. multiple design strategy interventions) for reporting cRCT=cluster randomized controlled trial; NA=not applicable; NRCT=non-randomized controlled trial; quasi=quasi-experimental study; RCT=randomized controlled trial

Conclusions

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NLM Citation

Table 62Health outcome study results (KQ1): summary and comparison of 2004 and 2010 systematic reviews

Table 63Numeracy outcome study results (KQ 1): summary of 2010 systematic review*

Table 64Results of intervention studies with single design strategies (KQ 2): summary and comparison of 2004 and 2010 systematic reviews *

Table 65Results of interventions with multiple design strategies: summary and comparison of 2004 and 2010 systematic reviews*

Table 63Numeracy outcome study results (KQ 1): summary of 2010 systematic review^*

Table 64Results of intervention studies with single design strategies (KQ 2): summary and comparison of 2004 and 2010 systematic reviews ^*

Table 65Results of interventions with multiple design strategies: summary and comparison of 2004 and 2010 systematic reviews^*