In this study conducted by the Kaiser Permanente Division of Research and the University of Washington School of Medicine, 72 percent of the 1,366 study participants had limited health literacy, and had significantly poorer adherence to newly prescribed antidepressants, compared to patients with no limitations.
“Research shows that those with health literacy limitations are more likely to have poor control of their chronic medical conditions such as diabetes, congestive heart failure and HIV,” said Andrew Karter, PhD, research scientist at Kaiser Permanente and senior author on the study. “However, this is the first study to examine the association between health literacy and antidepressant adherence among patients with diabetes. This type of research gives our health care systems important feedback because, as providers, we often remain unsure whether the critical health information we convey to our patients is fully understood.”
The Institute of Medicine defines health literacy as the capacity for patients to “obtain, process, and understand basic health information and services needed to make appropriate health decisions.” Because nearly 90 percent of Americans have some difficulty using routine health information, the U.S. surgeon general has identified the improvement of health literacy as a national priority.
Adequate adherence for antidepressants is particularly important for patients with diabetes and other chronic medical conditions. Depression occurs twice as frequently among adults with diabetes compared to adults without diabetes, and has been associated with an increased risk of the serious diabetic complications, dementia and mortality.
In the study, health literacy was based on a self-reported scale in which participants with type 2 diabetes responded to three questions:
• How often do you have problems learning about your medical condition because of difficulty understanding written information?
• How confident are you filling out medical forms by yourself?
• How often do you have someone like a family member, friend, hospital or clinic worker or caregiver, help you read health plan materials?
The study examined medication nonadherence during the 12 months after the initial antidepressant prescription, and researchers found that many patients failed to adhere to their treatment. Although most patients filled the prescription at least once, 43 percent failed to fill the prescription a second time, and nearly two-thirds had discontinued the antidepressant by the end of the 12-month period.
Poor adherence to antidepressant medications has been described previously, but what was not known is that those with health-literacy limitations were significantly less likely to take their antidepressant medications. In fact, diabetes patients with limited health literacy were much less likely to refill their antidepressant medications in a timely fashion than patients with no limitations. These patterns were not explained by other factors known to be associated with medication nonadherence, including age, race/ethnicity, English proficiency and income, which were accounted for in the study.
Depression in adults with diabetes is frequently chronic, suggesting the need for long-term antidepressant therapy. “The high rates of early discontinuation that were observed among adults with diabetes who had any health literacy limitation suggest that few of these individuals received an adequate course of antidepressant therapy. Getting that sufficient treatment is critical in preventing relapse and recurrence of depression,” said lead author Amy Bauer, MD, of the University of Washington School of Medicine. “Physicians should be aware of this. For antidepressant treatment to succeed, patients with limited health literacy may require more intensive counseling and clearer explanations about use of antidepressant medications and closer follow-up.”
The researchers said the study findings underscore the importance of national efforts to address healthy literacy, simplify health communications regarding treatment options, improve public understanding of the importance of depression treatment, and monitor antidepressant adherence.
Additional authors on the study include Wayne Katon, MD, University of Washington; Dean Schillinger, MD, University of California, San Francisco Division of General Internal Medicine; Melissa Parker, MS, Alyce Adams, PhD, and Howard H. Moffet, MPH, Kaiser Permanente Northern California Division of Research; and Nancy Adler, PhD, University of California, San Francisco Center for Health and Community.
This research was supported by funding from the National Institutes of Health.
About Research at University of Washington School of Medicine
Established in 1946, the UW School of Medicine has grown quickly into a highly productive, highly collaborative research community with excellent scientific resources and facilities. UW Medicine is ranked 12th in the nation among academic biomedical research institutions by U.S. News & World Report, and first among public medical schools in National Institutes of Health funding. Within the UW Medicine organization, the School of Medicine receives more than $600 million per year in NIH funding. In our history we have had five Nobel laureates and many members of the National Academy of Sciences and the Institute of Medicine. Our research achievements have had tremendous impact on the daily lives of Americans, through discoveries and innovations that help patients and offer new knowledge that advances our understanding of health and disease at the deepest levels. Research takes place within 30 academic departments and numerous interdisciplinary centers and institutes. Our graduate education programs in the biomedical sciences are a critical part of our commitment to research and discovery, and to the training of the next generation of scientists and innovators. For more information, visit: http://www.uwmedicine.org/Research/About.
About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and the society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 500-plus staff is working on more than 250 epidemiological and health services research projects. For more information, visit www.dor.kaiser.org.
About Kaiser Permanente
Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America’s leading health care providers and not-for-profit health plans. Founded in 1945, our mission is to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve more than 9 million members in nine states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, visit: kp.org/newscenter.