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Evidence Report/Technology Assessment Number 199 Health Literacy Interventions and Outcomes: An Updated Systematic Review Prepared for: Agency for Healthcare Research and Quality U.S. Department of Health and Human Services 540 Gaither Road Rockville, MD 20850 www.ahrq.gov Contract No. 290-2007-10056-I Prepared by: RTI International–University of North Carolina Evidence-based Practice Center Research Triangle Park, North Carolina Investigators: Nancy D. Berkman, Ph.D., M.L.I.R. Stacey L. Sheridan, M.D., M.P.H. Katrina E. Donahue, M.D., M.P.H. David J. Halpern, M.D., M.P.H. Anthony Viera, M.D., M.P.H. Karen Crotty, Ph.D., M.P.H. Audrey Holland, M.P.H. Michelle Brasure, Ph.D. Kathleen N. Lohr, Ph.D. Elizabeth Harden, M.P.H. Elizabeth Tant, B.A. Ina Wallace, Ph.D. Meera Viswanathan, Ph.D. AHRQ Publication No. 11-E006 March 2011

ii This document is in the public domain and may be used and reprinted without special permission. Citation of the source is appreciated. None of the investigators have any affiliations or financial involvement that conflicts with the material presented in this report. Suggested citation: Berkman ND, Sheridan SL, Donahue KE, Halpern DJ, Viera A, Crotty K, Holland A, Brasure M, Lohr KN, Harden E, Tant E, Wallace I, Viswanathan M. Health Literacy Interventions and Outcomes: An Updated Systematic Review. Evidence Report/Technology Assesment No. 199. (Prepared by RTI International–University of North Carolina Evidence- based Practice Center under contract No. 290-2007-10056-I. AHRQ Publication Number 11- E006. Rockville, MD. Agency for Healthcare Research and Quality. March 2011. This report is based on research conducted by the RTI International–University of North Carolina at Chapel Hill, North Carolina (RTI-UNC) Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-2007-10056-I). The findings and conclusions in this document are those of the author(s), who are responsible for its contents the findings and conclusions do not necessarily represent the views of AHRQ. Therefore, no statement in this article should be construed as an official position of the Agency for Healthcare Research and Quality or of the U.S. Department of Health and Human Services. The information in this report is intended to help health care decision-makers, patients and clinicians, health system leaders, and policymakers make well-informed decisions and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of clinical judgment. Decisions concerning the provision of clinical care should consider this report in the same way as any medical reference and in conjunction with all other pertinent information, i.e., in the context of available resources and circumstances presented by individual patients. This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

iii Preface The Agency for Healthcare Research and Quality (AHRQ), through its Evidence-based Practice Centers (EPCs), sponsors the development of evidence reports and technology assessments to assist public- and private-sector organizations in their efforts to improve the quality of health care in the United States. The reports and assessments provide organizations with comprehensive, science-based information on common, costly medical conditions and new health care technologies. The EPCs systematically review the relevant scientific literature on topics assigned to them by AHRQ and conduct additional analyses when appropriate prior to developing their reports and assessments. To bring the broadest range of experts into the development of evidence reports and health technology assessments, AHRQ encourages the EPCs to form partnerships and enter into collaborations with other medical and research organizations. The EPCs work with these partner organizations to ensure that the evidence reports and technology assessments they produce will become building blocks for health care quality improvement projects throughout the Nation. The reports undergo peer review prior to their release. AHRQ expects that the EPC evidence reports and technology assessments will inform individual health plans, providers, and purchasers as well as the health care system as a whole by providing important information to help improve health care quality. We welcome comments on this evidence report. They may be sent by mail to the Task Order Officer named below at: Agency for Healthcare Research and Quality, 540 Gaither Road, Rockville, MD 20850, or by e-mail to epc@ahrq.gov. Carolyn M. Clancy, M.D. Director Agency for Healthcare Research and Quality Jean Slutsky, P.A., M.S.P.H. Director, Centre for Outcomes and Evidence Agency for Healthcare Research and Quality Marian James, Ph.D., M.A. EPC Program Task Order Officer Agency for Healthcare Research and Quality Stephanie Chang, M.D., M.P.H. Director, EPC Program Agency for Healthcare Research and Quality

iv Acknowledgments This study was supported by Contract 290-2007-10056-I from the Agency for Healthcare Research and Quality (AHRQ), Task No. 5. We acknowledge the continuing support of Stephanie Chang, M.D., M.P.H., Director of the AHRQ Evidence-based Practice Center (EPC) Program, and Marian D. James, Ph.D., M.A., the AHRQ Task Order Officer for this project. We extend our appreciation to our Technical Expert Panel (TEP). All provided thoughtful advice and input during our research process. The TEP was both a substantive resource and a “sounding board” throughout the study. It was also the body from which expertise was formally sought at several junctions. The investigators would like to particularly thank Cindy Brach for her assistance in querying intervention study researchers. TEP members are listed below: Michael Paasche-Orlow, M.D., M.A., M.P.H. Internal Medicine, Boston University School of Medicine Boston, MA Marilyn Shapira, M.D., M.P.H. Medical College of Wisconsin Milwaukee, WI Cindy Brach, M.P.P. Agency for Healthcare Research and Quality Rockville, MD David Baker, M.D. Internal Medicine, Northwestern University Chicago, IL Darren DeWalt, M.D. Internal Medicine, University of North Carolina Chapel Hill, NC Rima Rudd, Sc.D. Harvard School of Public Health Boston, MA Sue Stableford, M.P.H., M.S.B. Health Literacy Institute, University of New England Portland, ME Joanne Schwartzberg, M.D. American Medical Association Chicago, IL The investigators deeply appreciate the considerable support, commitment, and contributions of the EPC team staff at RTI International and the University of North Carolina at Chapel Hill. We express our gratitude to Megan Van Noord, M.S.I.S., Christiane Voisin, M.S.L.S., and Lynn Whitener, M.S.L.S., Dr.P.H. our EPC Librarians Loraine Monroe, our EPC publications specialist Jennifer Drolet, M.A., our editor and Linda Lux, M.P.A., the RTI-UNC Administrator. We would also like to thank Shrikant Bangdiwala, Ph.D. for his helpful consultation on questions related to statistical methodology included in the literature. Finally, we would like to thank Michael Pignone and Darren Dewalt, who were our collaborators on the original review we performed in 2004 our discussions and work with them provided a critical foundation for the current review.

v Health Literacy Interventions and Outcomes: An Updated Systematic Review Structured Abstract Objectives. To update a 2004 systematic review of health care service use and health outcomes related to differences in health literacy level and interventions designed to improve these outcomes for individuals with low health literacy. Disparities in health outcomes and effectiveness of interventions among different sociodemographic groups were also examined. Data sources. We searched MEDLINE,® the Cumulative Index to Nursing and Allied Health Literature, the Cochrane Library, PsychINFO, and the Educational Resources Information Center. For health literacy, we searched using a variety of terms, limited to English and studies published from 2003 to May 25, 2010. For numeracy, we searched from 1966 to May 25, 2010. Review methods. We used standard Evidence-based Practice Center methods of dual review of abstracts, full-text articles, abstractions, quality ratings, and strength of evidence grading. We resolved disagreements by consensus. We evaluated whether newer literature was available for answering key questions, so we broadened our definition of health literacy to include numeracy and oral (spoken) health literacy. We excluded intervention studies that did not measure health literacy directly and updated our approach to evaluate individual study risk of bias and to grade strength of evidence. Results. We included good- and fair-quality studies: 81 studies addressing health outcomes (reported in 95 articles including 86 measuring health literacy and 16 measuring numeracy, of which 7 measure both) and 42 studies (reported in 45 articles) addressing interventions. Differences in health literacy level were consistently associated with increased hospitalizations, greater emergency care use, lower use of mammography, lower receipt of influenza vaccine, poorer ability to demonstrate taking medications appropriately, poorer ability to interpret labels and health messages, and, among seniors, poorer overall health status and higher mortality. Health literacy level potentially mediates disparities between blacks and whites. The strength of evidence of numeracy studies was insufficient to low, limiting conclusions about the influence of numeracy on health care service use or health outcomes. Two studies suggested numeracy may mediate the effect of disparities on health outcomes. We found no evidence concerning oral health literacy and outcomes. Among intervention studies (27 randomized controlled trials [RCTs], 2 cluster RCTs, and 13 quasi-experimental designs), the strength of evidence for specific design features was low or insufficient. However, several specific features seemed to improve comprehension in one or a few studies. The strength of evidence was moderate for the effect of mixed interventions on health care service use the effect of intensive self-management inventions on behavior and the effect of disease-management interventions on disease prevalence/severity. The effects of other mixed interventions on other health outcomes, including knowledge, self-efficacy, adherence, and quality of life, and costs were mixed thus, the strength of evidence was insufficient. Conclusions. The field of health literacy has advanced since the 2004 report. Future research priorities include justifying appropriate cutoffs for health literacy levels prior to conducting studies developing tools that measure additional related skills, particularly oral (spoken) health

vi literacy and examining mediators and moderators of the effect of health literacy. Priorities in advancing the design features of interventions include testing novel approaches to increase motivation, techniques for delivering information orally or numerically, “work around” interventions such as patient advocates determining the effective components of already-tested interventions determining the cost-effectiveness of programs and determining the effect of policy and practice interventions.

vii Contents Executive Summary.................................................................................................................ES-1 Introduction ....................................................................................................................................1 Health Literacy.....................................................................................................................1 Definition .................................................................................................................1 Burden of Low Literacy and Low Health Literacy ..............................................................1 Measuring Health Literacy ..................................................................................................3 Relationship Between Health Literacy and Outcomes ........................................................8 Effects of Interventions To Reduce Burden of Low Health Literacy ..................................9 Need for Update of the Earlier Review ................................................................................9 Production of This Report ..................................................................................................10 Organization ...........................................................................................................10 Technical Expert Panel ......................................................................................................10 Use of This Updated Systematic Review...........................................................................11 Methods .........................................................................................................................................12 Key Questions and Analytic Framework ...........................................................................15 Literature Search and Retrieval Process ............................................................................17 Database Search Terms ..........................................................................................17 Study Selection Process .....................................................................................................17 Inclusion and Exclusion Criteria ............................................................................17 Process for Considering Abstracts and Full Articles for Inclusion....................................20 Literature Synthesis ...........................................................................................................21 Development of Evidence Tables and Data Abstraction Process ......................................21 Quality Rating of Individual Studies .................................................................................21 Data Synthesis ....................................................................................................................22 Grading the Strength of Available Evidence .....................................................................22 Applicability of the Evidence ............................................................................................23 Peer Review Process ..........................................................................................................23 Results: Relationship of Health Literacy to Outcomes and Disparities..................................24 Results of Literature Search ...............................................................................................26 Key Question 1. Relationship of Health Literacy to Various Outcomes and Disparities ..........................................................................................................................26 KQ 1a. Use of Health Care Services ......................................................................27 Summary of Outcomes on Use of Health Care Services ...................................................30 KQ 1b. Health Outcomes .......................................................................................30 Summary of Outcomes and Strength of Evidence on Health Outcomes ...........................39 KQ 1c. Costs of Health Care..................................................................................39 KQ 1d. Disparities in Health Outcomes or Health Care Service Use ....................40 Key Question 1. Relationship of Numeracy to Various Outcomes and Disparities ..........41 KQ 1a. Use of Health Care Services ......................................................................41 KQ 1b. Health Outcomes .......................................................................................42 KQ 1c. Costs ..........................................................................................................45 KQ 1d. Potential Mediator of Disparities ..............................................................45 The Effect of Interventions To Mitigate the Effects of Low Health Literacy ......................143 Introduction ......................................................................................................................143 Search Results ..................................................................................................................143

viii Study Quality ...................................................................................................................144 Characteristics of Included Studies ..................................................................................144 Effects of Health Literacy Interventions Using Single Strategies, by Intervention Type .................................................................................................................................144 Intervention: Alternative Document Design ........................................................144 Intervention: Alternative Numerical Presentation ...............................................145 Intervention: Additive and Alternative Pictorial Representation .........................146 Intervention: Alternative Media ...........................................................................148 Intervention: Alternative Readability and Document Design ..............................150 Intervention: Physician Notification of Patient Literacy Status ..........................151 Summary of Interventions Using Single Intervention Design Strategies ............151 Effects of Mixed Strategy Interventions, by Analytic Framework ..................................152 KQ 2a. Effect of Mixed Interventions on Use of Health Care Services ..............152 KQ 2b. Effect of Mixed Interventions on Health Outcomes ...............................153 KQ 2c. Effect of Mixed Interventions on Health Care Costs ..............................157 KQ 2d. Effect of Mixed Interventions on Disparities ..........................................158 Summary of Interventions Using Mixed Intervention Strategies ....................................158 Cross-Cutting Observations About Interventions Designed To Mitigate Low Health Literacy ............................................................................................................................158 Discussion....................................................................................................................................216 Overview ..........................................................................................................................216 Principal Findings ............................................................................................................216 KQ 1. Health Literacy and Outcomes ..................................................................216 KQ 2. Interventions To Improve Health Literacy ................................................218 What This Update Adds to the Literature Included in the 2004 Review .........................220 Limitations .......................................................................................................................221 Limitations of the Literature ............................................................................................221 Limitations of Our Review ..............................................................................................222 Opportunities for Future Research ...................................................................................223 Future Research Into the Relationship Between Health Literacy and Health Outcomes .........................................................................................................................223 Future Research Into Interventions To Mitigate the Effects of Low Health Literacy ............................................................................................................................224 Implications of This Report for Clinicians and Policymakers .........................................226 Conclusions .................................................................................................................................227 References ...................................................................................................................................232 Figures Figure A. Logic Model for Analyzing Studies of Health Literacy............................................ES-3 Figure 1. Analytic Framework for the Health Literacy Systematic Review..................................14 Figure 2. Logic Model for the Health Literacy Systematic Review..............................................15 Figure 3. PRISMA Tree: Flow Diagram Depicting Review and Disposition of Articles .............25 Tables Table 1. Measures of Health Literacy..............................................................................................4 Table 2. Measures of Numeracy ......................................................................................................7 Table 3. Inclusion/Exclusion Criteria for Studies Considered in This Update..............................20

ix Table 4. Strength of Evidence Grades and Definitions..................................................................23 Table 5. Overview of Health Literacy Studies...............................................................................46 Table 6. Measurement Tools and Criteria Used To Measure Health Literacy or Literacy in KQ 1 Articles .................................................................................................................................63 Table 7. Summary of Studies of the Relationship Between Health Literacy and Emergency Department and Hospitalization Rates (KQ 1a) ............................................................................66 Table 8. KQ 1a Health Literacy Studies: Strength of Evidence Grades by Health Care Service Outcomes ..........................................................................................................................69 Table 9. Summary of Studies of the Relationship Between Health Literacy and Colon Cancer Screening (KQ 1a) .............................................................................................................70 Table 10. Summary of Studies of the Relationship Between Health Literacy and Pap Tests (KQ 1a) ..........................................................................................................................................71 Table 11. Summary of Studies of the Relationship Between Health Literacy and Mammography (KQ 1a) ..........................................................................................................................................72 Table 12. Summary of Studies of the Relationship Between Health Literacy and Sexually Transmitted Infections Testing (KQ 1a) ........................................................................................73 Table 13. Summary of Studies of the Relationship Between Health Literacy and Immunizations (KQ 1a) ..........................................................................................................................................74 Table 14. Summary of Studies of the Relationship Between Health Literacy and Access to Care and Access to Insurance (KQ 1a) ...................................................................................................75 Table 15. Summary of Studies of the Relationship Between Health Literacy and Adherence (KQ 1b) ..........................................................................................................................................79 Table 16. KQ 1b Health Literacy Studies: Strength of Evidence Grades by Health Outcomes....84 Table 17. Summary of Studies of the Relationship Between Health Literacy and Self-Efficacy (KQ 1b) ..........................................................................................................................................86 Table 18. Summary of Studies of the Relationship Between Health Literacy and Health Behaviors (KQ 1b) .........................................................................................................................88 Table 19. Summary of Studies of the Relationship Between Health Literacy and the Outcome of Health Care Related Skills (KQ 1b) ...........................................................................93 Table 20. Summary of Studies of the Relationship Between Health Literacy and the Outcome of Prevalence of Depression and Other Mental Health Outcomes (KQ 1b) ......................................98 Table 21. Summary of Studies of the Relationship Between Health Literacy and the Outcome of Prevalence of Chronic Diseases (KQ 1b) ................................................................101 Table 22. Summary of Studies of the Relationship Between Health Literacy and HIV Patient Symptoms (KQ 1b) ..........................................................................................................105 Table 23. Summary of Studies of the Relationship Between Health Literacy and Asthma Patient Symptoms (KQ 1b) ......................................................................................................................106 Table 24. Summary of Studies of the Relationship Between Health Literacy and Diabetes Control (KQ 1b) ............................................................................................................107 Table 25. Summary of Studies of the Relationship Between Health Literacy and Hypertension Control (KQ 1b) .................................…………………………………………………………..111 Table 26. Summary of Studies of the Relationship Between Health Literacy and Prostate Cancer Control (KQ1b) ..................................................................................................112 Table 27. Summary of Studies of the Relationship Between Health Literacy and Health Status (KQ 1b) .............................................................................................................................112

x Table 28. Summary of Studies on the Relationship Between Health Literacy and Mortality (KQ 1b) ........................................................................................................................120 Table 29. Summary of Studies of the Relationship Between Health Literacy and Costs (KQ 1c) ........................................................................................................................................122 Table 30. KQ 1c Health Literacy Studies: Strength of Evidence Grades by Costs of Health Care ..................................................................................................................................123 Table 31. Summary of Studies of the Relationship Between Health Literacy and Disparities (KQ 1d) ......................................................................................................................124 Table 32. KQ 1d Health Literacy Studies: Strength of Evidence Grades by Disparities Across Health Outcomes..............................................................................................................128 Table 33. Overview of Numeracy Studies...................................................................................129 Table 34. The Relationship Between Numeracy Level and Use of Health Care Services (KQ 1a) ........................................................................................................................................132 Table 35. KQ 1 Numeracy Studies: Strength of Evidence Grades by Use of Health Care Services and Health Outcomes ....................................................................................................132 Table 36. The Relationship Between Numeracy Level and Accuracy of Risk Perception (KQ 1b) ........................................................................................................................................133 Table 37. Relationship Between Numeracy Level and Knowledge (KQ 1b) ..............................135 Table 38. Relationship Between Numeracy and Self-Efficacy (KQ 1b) .....................................136 Table 39. Relationship Between Numeracy Level and Behavior (KQ 1b) ..................................137 Table 40. Relationship Between Numeracy Level and Skills (KQ 1b) .......................................138 Table 41. Relationship Between Numeracy Level and Disease Prevalence and Severity (KQ 1b) ..........................................................................................................................141 Table 42. Relationship Between Numeracy Level and Disparities (KQ 1d) ...............................142 Table 43. Summary of Included Intervention Studies .................................................................160 Table 44. Intervention Study Detail.............................................................................................168 Table 45. Single Intervention Strategies: Alternative Document Design....................................178 Table 46. KQ 2 Specific Interventions: Strength of Evidence Grades by Type of Outcome......180 Table 47. Single Intervention Strategies: Alternative Numerical Presentation ..........………….182 Table 48. Single Intervention Strategies: Additive and Alternative Pictorial Representation ....185 Table 49. Single Intervention Strategies: Alternative Media.......................................................192 Table 50. Single Intervention Strategies: Alternative Readability and Document Design..........194 Table 51. Single Intervention Strategies: Physician Notification of Patient Literacy Levels .....198 Table 52. Effect of Mixed Interventions on Use of Health Care Services ..................................199 Table 53. KQ 2 Mixed Interventions: Strength of Evidence Grades by Type of Outcome.........201 Table 54. Effect of Mixed Interventions on Knowledge .............................................................202 Table 55. Effect of Mixed Interventions on Self-Efficacy ..........................................................204 Table 56. Effect of Mixed Interventions on Skills.......................................................................206 Table 57. Effect of Mixed Interventions on Behavior .................................................................207 Table 58. Effect of Mixed Interventions on Adherence ..............................................................208 Table 59. Effect of Mixed Interventions on Disease Prevalence and Severity............................210 Table 60. Effect of Mixed Interventions on Quality of Life........................................................213 Table 61. Effect of Mixed Interventions on Health Care Costs...................................................215 Table 62. Health Outcome Study Results (KQ 1): Summary and Comparison of 2004 and 2010 Systematic Reviews .....................................................................................................228

xi Table 63. Numeracy Outcome Study Results (KQ 1): Summary of 2010 Systematic Review .........................................................................................................................................230 Table 64. Results of Intervention Studies with Single Design Strategies (KQ 2): Summary and Comparison of 2004 and 2010 Systematic Reviews.............................................................230 Table 65. Results of Interventions with Multiple Design Strategies: Summary and Comparison of 2004 and 2010 Systematic Reviews ............................................................................................231 Appendixes Appendix A. Author Queries Appendix B. Search Strings Appendix C. Inclusion/Exclusion Criteria and Study Internal Validity Quality Form Appendix D. Evidence Tables Appendix E. Characteristics of Studies With Poor Internal Validity Appendix F. Strength of Evidence Appendix G. Peer Reviewers Appendix H. Excluded Studies Appendix I. Articles by Database Search Appendix J. Summary of KQ 1 Findings from Literacy and Health Outcomes Report

ES-1 Executive Summary Introduction Health literacy is “the degree to which individuals can obtain, process, and understand the basic health information and services they need to make appropriate health decisions.” It represents a constellation of skills necessary for people to function effectively in the health care environment and act appropriately on health care information. These skills include the ability to interpret documents, read and write prose (print literacy), use quantitative information (numeracy), and speak and listen effectively (oral literacy). Low health literacy is a significant problem in the United States. In 2003, approximately 80 million adults in the United States (36 percent) had limited health literacy. Rates of limited health literacy in certain population subgroups were higher. For instance, rates were higher among the elderly, minorities, individuals who have not completed high school, adults who spoke a language other than English before starting school, and people living in poverty. Highlighting the health impact of low health literacy, a 2004 systematic evidence review found a relationship between low health literacy and poor health outcomes. Specifically, health literacy (measured by reading skills) was associated with health-related knowledge and comprehension, hospitalization rates, global health measures, and some chronic diseases. Given the burden of low health literacy and the potential to reduce poor outcomes using novel interventions to address it, several national organizations have called for action. In 2010, the U.S. Department of Health and Human Services (HHS) released a National Action Plan to Improve Health Literacy. Additionally, in recent years, several national organizations and agencies, including the Institute of Medicine, American Medical Association, National Institutes of Health, and HHS (in Healthy People 2010), have promoted health literacy as a research priority. Researchers responded to these calls with new and more sophisticated work. Thus, to synthesize the increasing volume of literature on health literacy, the Agency for Healthcare Research and Quality (AHRQ) commissioned the RTI International−University of North Carolina Evidence-based Practice Center (EPC) to update its 2004 systematic review examining the effects of literacy on health outcomes and interventions to improve those outcomes. In this updated report, we focus on the same Key Questions as the original report: Key Question 1. Outcomes: Are health literacy skills related to (a) use of health care services, (b) health outcomes, (c) costs of health care, and (d) disparities in health outcomes or health care service use? Key Question 2. Interventions: For individuals with low health literacy skills, what are effective interventions to (a) improve use of health care services, (b) improve health outcomes, (c) affect the costs of care, and (d) improve health care service use and/or health outcomes among different racial, ethnic, cultural, or age groups? In contrast to our earlier report, we concentrate on “health literacy” rather than “literacy” for several reasons. First, we aimed to be consistent with recent conceptualizations of health literacy skills that separately examine print literacy, numeracy, and oral literacy. Second, an increasing

ES-2 number of newer measures are framed in specific health contexts and assess condition-related skills. Finally, measures of health literacy, print literacy (including prose and document literacy), and numeracy are highly correlated in national samples. Although we believe our focus on health literacy appropriately represents the directions of research and policy in this field, we acknowledge that the literature contributing to this field does not organize itself neatly within our health literacy framework. For instance, several measures of health literacy assess a combination of print literacy and numeracy skills, making distinctions between print literacy and numeracy difficult. Furthermore, the quantitative skills components of some measures have been extracted and used independently as measures of numeracy. To simplify this report, we separate health literacy (including any studies that presume to measure literacy or health literacy) from those that solely measure numeracy or oral literacy. Methods Changes From Our Prior Review Our overall goals in this update were to evaluate whether newer literature was appropriate for answering our Key Questions and to determine whether earlier conclusions changed. Following discussions with our Technical Expert Panel, we modified the original methods as follows: • We broadened our definition of health literacy to be consistent with the Ratzan and Parker (2000) definition used by Healthy People 2010 and the Institute of Medicine. Thus, our inclusion criteria included studies that measured numeracy and oral skills of participants. • We required that studies directly measured the health literacy of the study population and did not assign health literacy level via self-report or similarity to other populations. • To evaluate individual study quality, we incorporated advances in the methods of conducting systematic reviews. • We included studies conducted in developing countries as long as they used an objective measure of literacy or health literacy in their participants. • We reviewed knowledge as an outcome only for numeracy and intervention studies because evidence in the earlier review clearly concluded that greater literacy skills and higher health-related knowledge levels are positively related. • If articles about intervention studies were missing information about intervention content, we queried the investigators to allow richer interpretation about what interventions may be effective in mitigating the effects of low health literacy. Outcomes of Interest The logic model in Figure A details outcomes that we included in our review as well as other conceptually important variables. It draws on several models of health literacy proposed by researchers in the field and on an integrated model of behavioral theory called the Integrative Theory. We applied this model to determine whether studies considered for inclusion had relevant health outcomes and to guide our presentation of included articles. It is not, however, a definitive guide to the relationship among variables because researchers have not explicitly tested many of these relationships yet. Furthermore, it does not specify the directionality of a good outcome for some outcomes, increases represent the good outcome (e.g., adherence, most screening tests) and for others, decreases represent the good outcome (e.g., hospitalizations,

ES-3 mortality). We did not examine outcomes related to attitudes because of the belief that attitudes result from knowledge, which, as mentioned above, is not examined in the current report. Further, we did not examine outcomes related to social norms or patient-provider relationships (e.g., shared decisionmaking) because we thought that these variables likely affected the direction or strength of the relationship between behavioral intent and health outcomes, rather than laying on the causal pathway. Clearly, however, empiric work is needed to test these assertions prior to future reviews. Figure A. Logic model for analyzing studies of health literacy Literature Search and Retrieval Process We searched MEDLINE,® Article Review and Data Abstraction the Cumulative Index to Nursing and Allied Health Literature, the Cochrane Library, PsycINFO, and the Educational Resources Information Center. For health literacy, we searched from 2003 to May 25, 2010. For numeracy, we searched from 1966 to May 25, 2010. We conducted keyword searches because no Medical Subject Headings terms specifically identify health-literacy-related articles. The terms health literacy, numeracy, and literacy, and terms or phrases related to instruments known to measure health literacy and numeracy, were the focus of the search. We excluded editorials, letters to the editor, case reports, and non-English language studies. We also manually searched reference lists of pertinent review articles and editorials for additional studies. We used standard EPC methods for dual review of abstracts and full text of articles to determine article inclusion. After determining article inclusion, one reviewer entered data about studies into evidence tables and a second, senior reviewer checked information for accuracy and completeness. Quality Review Two reviewers independently rated the quality of studies (good, fair, or poor) using criteria designed to detect selection bias, measurement bias, confounding, and inadequate power. Reviewers resolved all disagreements about quality ratings by consensus. We did not consider further any studies that we rated poor quality.