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Low Health Literacy and Health Outcomes: An Updated Systematic Review

Nancy D. Berkman, PhD; Stacey L. Sheridan, MD, MPH; Katrina E. Donahue, MD, MPH; David J. Halpern, MD, MPH; and Karen Crotty, PhD, MPH
[+] Article and Author Information

From RTI International, Research Triangle Park; University of North Carolina at Chapel Hill, Chapel Hill; and Duke University, Durham, North Carolina.


Disclaimer: The authors of this report are responsible for its content. Statements in this report should not be construed as endorsement by the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.

Acknowledgment: The authors thank Audrey R. Holland, Anthony J. Viera, Loraine G. Monroe, Michelle Brasure, Elizabeth Harden, Elizabeth Tant, and Ina F. Wallace for their assistance in conducting the systematic review. They also thank Kathleen N. Lohr, Meera Viswanathan, and Dan Jonas for their input on standard Agency for Healthcare Research and Quality Evidence-based Practice Center protocols. Finally, they thank Kathleen N. Lohr, Anthony J. Viera, and Jonathan M. Farber for their input on prior drafts of this manuscript and Loraine G. Monroe for her assistance in preparing the manuscript.

Financial Support: This project was funded by the Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services (under contract HHSA-290-2007-10056-1).

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M11-0110.

Requests for Single Reprints: Nancy D. Berkman, PhD, Program on Health Care Quality and Outcomes, Division of Health Services and Social Policy Research, RTI International, PO Box 12194, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194; e-mail: berkman@rti.org.

Current Author Addresses: Dr. Berkman: Program on Health Care Quality and Outcomes, Division of Health Services and Social Policy Research, RTI International, PO Box 12194, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194.

Dr. Sheridan: 5039 Old Clinic Building, CB 7110, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.

Dr. Donahue: Department of Family Medicine, University of North Carolina at Chapel Hill, CB 7595, 590 Manning Drive, Chapel Hill, NC 27599.

Dr. Halpern: Durham Medical Center, 4220 North Roxboro Road, Durham, NC 27704.

Dr. Crotty: W228 S2406 Oriole Drive, Waukesha, WI 53186.

Author Contributions: Conception and design: N.D. Berkman, S.L. Sheridan, K.E. Donahue, D.J. Halpern.

Analysis and interpretation of the data: N.D. Berkman, S.L. Sheridan, K.E. Donahue, D.J. Halpern, K. Crotty.

Drafting of the article: N.D. Berkman, S.L. Sheridan, K.E. Donahue, D.J. Halpern.

Critical revision of the article for important intellectual content: N.D. Berkman, S.L. Sheridan, K.E. Donahue, D.J. Halpern, K. Crotty.

Final approval of the article: N.D. Berkman, S.L. Sheridan, K.E. Donahue, D.J. Halpern.

Statistical expertise: D.J. Halpern.

Obtaining of funding: N.D. Berkman, S.L. Sheridan.

Administrative, technical, or logistic support: N.D. Berkman, K. Crotty.

Collection and assembly of data: N.D. Berkman, S.L. Sheridan, K.E. Donahue, D.J. Halpern, K. Crotty.


Ann Intern Med. 2011;155(2):97-107. doi:10.7326/0003-4819-155-2-201107190-00005
Text Size: A A A

Background: Approximately 80 million Americans have limited health literacy, which puts them at greater risk for poorer access to care and poorer health outcomes.

Purpose: To update a 2004 systematic review and determine whether low health literacy is related to poorer use of health care, outcomes, costs, and disparities in health outcomes among persons of all ages.

Data Sources: English-language articles identified through MEDLINE, CINAHL, PsycINFO, ERIC, and Cochrane Library databases and hand-searching (search dates for articles on health literacy, 2003 to 22 February 2011; for articles on numeracy, 1966 to 22 February 2011).

Study Selection: Two reviewers independently selected studies that compared outcomes by differences in directly measured health literacy or numeracy levels.

Data Extraction: One reviewer abstracted article information into evidence tables; a second reviewer checked information for accuracy. Two reviewers independently rated study quality by using predefined criteria, and the investigative team jointly graded the overall strength of evidence.

Data Synthesis: 96 relevant good- or fair-quality studies in 111 articles were identified: 98 articles on health literacy, 22 on numeracy, and 9 on both. Low health literacy was consistently associated with more hospitalizations; greater use of emergency care; lower receipt of mammography screening and influenza vaccine; poorer ability to demonstrate taking medications appropriately; poorer ability to interpret labels and health messages; and, among elderly persons, poorer overall health status and higher mortality rates. Poor health literacy partially explains racial disparities in some outcomes. Reviewers could not reach firm conclusions about the relationship between numeracy and health outcomes because of few studies or inconsistent results among studies.

Limitations: Searches were limited to articles published in English. No Medical Subject Heading terms exist for identifying relevant studies. No evidence concerning oral health literacy (speaking and listening skills) and outcomes was found.

Conclusion: Low health literacy is associated with poorer health outcomes and poorer use of health care services.

Primary Funding Source: Agency for Healthcare Research and Quality.

Figures

Grahic Jump Location
Appendix Figure.
Summary of evidence search and selection.

KQ = key question.

Grahic Jump Location

Tables

References

Letters

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Comments

Submit a Comment
Missing Elements
Posted on July 24, 2011
Rima E. Rudd
Harvard School of Public Health
Conflict of Interest: None Declared

The updated systematic review of low health literacy and outcomes by Berkman and colleagues published 19 July offers a rigorous examination of health literacy studies from 2004 until a year or so ago. Missing from the review is an acknowledgment of the narrowness of current inquiry and an examination of explanatory models offered or missing from the various studies under consideration.

Many health literacy studies offer no theoretical or logical explanation of the link between literacy skills and health outcomes or justification for studying patients' abilities without due attention to the demand side. As the 2004 Institute of Medicine report indicated, literacy is the result of an interaction - for example between a reader and a text or a listener and a speaker. One cannot fairly examine an individual's reading skills or listening skills without considering the skills of the writer or of the speaker. Unfortunately, few health literacy studies have expanded the focus beyond the skills and abilities of the consumer/patient to include the skills and abilities of providers of information and care. As a result, the somewhat myopic examinations of patients' literacy skills may appear to squarely place the blame for untoward health on patients' deficits. Yet, we know that access to information and instructions can be denied when it is shrouded in jargon and unexplained scientific terms and in poorly organized or cumbersome format. This mismatch between what people need and what we in the various health fields offer is certainly unhealthy and can be deadly.

We have had clear evidence of U.S. adults' limited literacy skills since the findings from the US Department of Education's first rigorous survey, published in 1993. We know too after more than a decade of health studies as this and earlier reviews have indicated, that patients with poor literacy skills face poor health outcomes in terms of increased morbidity and mortality. Yet, we have done little to make adjustments in communication to improve health information and tools in print, on line, in discussion, or over the airwaves. Furthermore, we have not rigorously studied professionals' communication content and style to explore the links between our communication and untoward health outcomes.

The field of health literacy inquiry must expand beyond an examination of links between patients' skills and health outcomes if we are to understand and eliminate the unnecessary literacy related barriers patients face and improve health outcomes. Studies reflected in current publications have been limited and the focus on one part of the equation has hobbled our understanding of health literacy issues. Perhaps further reviews will consider the assumptions and theory underlying the various studies, to make this limitation more overt.

Conflict of Interest:

None declared

Re:Missing Elements
Posted on July 27, 2011
Joy C Burnette, RN, BSN
Atlanta Heart Group
Conflict of Interest: None Declared

I must agree that there are many facets of the health literacy issue that remain unexamined. I do believe that as our colleagues become more aware of the problem we will see more of a robust investigational approach to include patient-provider communication, patient learning styles, teaching methods, specific readability scales for health related information and many other areas related to health literacy.

Our anticoagulation clinic regularly measures health literacy using the Rapid Estimate of Adult Literacy in Medicien short form (REALM-SF)and we then provide health literacy appropriate communication and written literature. While the REALM-SF does not measure comprehension it is a better measure of individual health literacy than highest education level attained. Our anecdotal experience has been that the highest education level attain is a mediocre indicator for health literacy.

What is also lacking are interventions and if those intervention improve health literacy. If we improve health literacy do clinical outcomes improve as well?

This is an area of great interest for nurses as we provided the bulk of patient education in the acute and long-term settings. There are several initiatives to improve health literacy including the National Action Plan to Improve Health Literacy. You may find information on this plan at http://www.health.gov/communication/hlactionplan/

This is a very important topic and deserving of robust research and clinical translation of findings.

Conflict of Interest:

Alere consultant

Low Health Literacy and Health Outcomes: An Updated Systematic Review", 2011
Posted on August 9, 2011
Lindsay Rosenfeld
NE University
Conflict of Interest: None Declared

Dear Editor:

The comprehensive review, "Low Health Literacy and Health Outcomes: An Updated Systematic Review", published in the Annals of Internal Medicine, July 2011 and presented as a full AHRQ Report (March 2011), updates the health literacy literature since 2004. I write with appreciation for this substantial undertaking and to include an update. The authors state that "no evidence concerning oral health literacy (speaking and listening skills) and outcomes was found". There is indeed literature in the field that addresses oral literacy and health outcomes.

Several studies have focused on the importance of dialogue in health -- addressing oral and aural literacy. Roter (2007, 2009, 2011) and Koch- Weser, et. al. (2010), have discussed measures of oral literacy (1,2,3,4). Two studies, examining the relationship between oral literacy and health outcomes, measured skills with the Woodcock Johnson Achievements Tests, reported as grade equivalents. Rosenfeld, et. al. found a statistically significant association between study participants with lower aural literacy skills and less successful asthma management. Martin, et. al. 2011 found that reading, numeracy and aural language skills were significantly associated with coronary heart disease risk among women (5).

I look forward to a more expansive agenda in health literacy -- one that broadens the notion of literacy beyond attention to the written word and one that broadens the focus of interest to include the skills of health providers and the expectations of health systems. This is aptly noted in Rudd's (2011) letter about this review in the Annals (6).

Respectfully submitted,

Lindsay Rosenfeld, ScD, ScM

References:

1. Roter DL., Erby LH., Larson S., Ellington L. (2007). Assessing oral literacy demand in genetic counseling dialogue: preliminary test of a conceptual framework. Social Science and Medicine, 65(7), 1442-1457.

2. Roter DL., Erby L., Larson S., Ellington L. (2009). Oral literacy demand of prenatal genetic counseling dialogue: Predictors of learning. Patient Education and Counseling, 75(3), 392-397.

3. 6. Roter, DL. (2011). Oral literacy demand of health care communication: challenges and solutions. Nursing Outlook, 59(2), 79-84.

4. Koch-Weser, S., Rudd RE., DeJong, W. (2010). Quantifying Word-Use to Study Health Literacy in Doctor-Patient Communication. Journal of Health Communication, 15(6), 590-602.

5. Martin, LT., Schonlau, M., Haas, A., Pitkin Derose, K., Rudd, R., Loucks EB., Rosenfeld, L., Buka, SL. (2011). Literacy Skills and Calculated 10-Year Risk of Coronary Heart Disease. Journal of General Internal Medicine, 26(1), 45-50.

6. Rosenfeld, L., Rudd, R., Emmons, KM, Acevedo-Garc?a, D., Martin, L., Buka, S. (2011). Beyond Reading Alone: The relationship between aural literacy and asthma management. Patient Education and Counseling, 82(1), 110-6.

Conflict of Interest:

None declared

Actual Patients Should be Studied
Posted on August 15, 2011
Hema Padmanabhan
No Affiliation
Conflict of Interest: None Declared

TO THE EDITOR: This article (1) makes for interesting reading. Being a systematic review of selected studies dealing with articles on "health literacy", and numeracy it highlights only the results deduced by reviewers' analyses of abstracted articles in tabular form, and rating study quality by predefined criteria. Based on "health literacy" skills (2) the study does conclude that low literacy is associated with poorer health outcomes and poorer use of health care services. The major limitation of the study is that actual patients were not studied. Education level, socio economic status, and different healthcare settings where care is rendered (clinic, hospital or emergency room etc) also influence outcomes. Although patient outcome may be influenced by "health literacy" it is also affected profoundly by how much time is spent in explaining to patients about their disease/ management and how well it is discussed without using too many complicated medical jargon. In today's health care delivery system where quantity of patients (and not quality of care) is emphasized, less attention is paid to the doctor-patient discussion. Even the most literate patient may be unable to understand the various diseases and more so the complex treatments involved, given the paucity of time a doctor spends with each patient. On the other hand even the most "health illiterate" patient may have a good outcome if he/she is self- motivated and informed, has adequate insurance coverage and a strong family/social support. This study also does not dwell on the demographics since patients living in rural and outlying areas are known to fare poorly as compared to those living in urban/suburban areas due to lack of easy access to emergent care(3,4,5).So it is not just "health literacy" which affects the ultimate outcome .

Hema Padmanabhan, MD, FACP Silver Spring, MD

References

1.Berkman ND, Sheridan SL, Donahue EK, Halpern DJ, Crotty K. Low health literacy and health outcomes: An updated systemic review. Ann Intern Med.2011; 155: 97-107.

2. Baker DW. The meaning and measure of health literacy. J Gen Intern Med. 2006; 21:878-83.

3. Hassan A, Pearce NJ, Mathers J, Veugelers PJ, Hirsch GM, Cox JL; improving cardiovascular outcomes in Nova Scotia Investigators.The effect of place of residence on access to invasive cardiac services following acute myocardial infarction. Can J Cardiolo.2009; 25:207-12.

4. Laditka JN, Laditka SB, Probst JC.Health care access in rural areas: evidence that hospitalization for ambulatory care-sensitive conditions in the United States may increase with the level of rurality. Heralds Place.2009; 731-40

5. Weeks WB,Kazis LE, Shen Y, Cong Z, Ren XS, Miller D , et al.Differences in health-related quality of life in rural and urban veterans. Am J Public Health.2004; 94:1762-67.

Conflict of Interest:

None declared

Author's response
Posted on October 5, 2011
Nancy D. Berkman
RTI International, Research Triangle Park, NC 27709
Conflict of Interest: None Declared

Health literacy is a set of skills that people need to function effectively in the health care environment, including reading and understanding text, locating information in documents, using numerical information (measuring, counting, ratios), and speaking and listening effectively. We examined the relationship between relative shortcomings in these skills (referred to as low health literacy) and poorer health outcomes (1).

Based on our systematic review of 96 studies, we agree with Dr. Rudd that future studies examining the relationship between individuals' health literacy level and their health outcomes would be enhanced by including analytic frameworks that thoughtfully conceptualize the link between the two. Some studies have considered more thoroughly the complexity of this relationship; they have examined the role of other, potentially intervening factors on outcomes; e.g., prior knowledge and beliefs about one's medical condition and level of self-efficacy. More patient-oriented research examining how these and other characteristics can affect outcomes for individuals with low health literacy (as Dr. Padmanabhan calls for) is needed.

Like Drs. Rudd, Padmanabhan, and Burnette, we appreciate that this body of literature does not evaluate the skills of the writer or the speaker. Thus, it cannot provide insight into what occurred in the "black box" of health information or personal medical encounters to help explain why outcomes were poorer for lower-literacy patients. However, it does take the necessary first step of assembling credible evidence of a relationship between low health literacy and important health outcomes. Showing this link does not imply that researchers and the readers of their studies are likely to place the blame for poor outcomes on individual patients Of course, documenting this relationship does not tell us what can be done to correct it. This review was part of a larger project that also examined the evidence on interventions to assist individuals with low health literacy (2, 3). Although much more needs to be understood about effective interventions, researchers are beginning to consider not only approaches to improving the presentation and communication of information but also more complex strategies to improve more distal health outcomes. Dr. Rosenfeld calls our attention to two studies that had not yet been indexed in PubMed using the MeSH term "Health Literacy" at the time of our review (4, 5). These studies introduce to the field the term "aural literacy," providing a useful distinction between listening (aural) and speaking (oral) skills. I appreciate having the opportunity to respond to these thoughtful letters.

Nancy D. Berkman, PhD RTI International Research Triangle Park, NC 27709

References:

1. Berkman ND, Sheridan SL, Donahue KE, et al. Low health literacy and health outcomes: an updated systematic review. Annals of internal medicine. 2011 Jul 19;155(2):97-107. PMID: 21768583.

2. Berkman ND, Sheridan SL, Donahue KE, et al. Health literacy interventions and outcomes: an update of the literacy and health outcomes systematic review of the literature Agency for Healthcare Research and Quality. AHRQ Publication Number 11-E006. (Prepared by RTI International- University of North Carolina Evidence-based Practice Center under Contract No. 290-2007-10056-I). Rockville, MD: 2011.

3. Sheridan SL, Halpern DJ, Viera AJ, et al. Interventions for individuals with low health literacy: a systematic review. J Health Commun. 2011;16(3):30-54.

4. Rosenfeld L, Rudd R, Emmons KM, et al. Beyond reading alone: the relationship between aural literacy and asthma management. Patient Education and Counseling. 2011 Jan;82(1):110-6. PMID: 20399060.

5. Martin LT, Schonlau M, Haas A, et al. Literacy skills and calculated 10-year risk of coronary heart disease. Journal of general internal medicine. 2011 Jan;26(1):45-50. PMID: 20809155.

Conflict of Interest:

None declared

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