"Lower socioeconomic status (SES) – less education and lower income and wealth – has for some time been strongly linked with poorer health," says James P. Smith, Ph.D., RAND, who conducted the research with colleague Dana P. Goldman, Ph.D. "This research offers a new and practical explanation for why these differences in health may occur and how we might address them." Smith notes that experts have looked at a number of possible explanations for health disparities associated with SES, including differences in access to health care and insurance or in smoking and drinking among high and low SES groups, but exactly how these factors contribute to differences in health is unclear.
Goldman and Smith's report appears in the July 22-26, 2002, online issue of the Proceedings of the National Academy of Sciences (PNAS). The research was supported by the National Institute on Aging (NIA), part of the National Institutes of Health, U.S. Department of Health and Human Services.
"This report takes a clever and useful approach to looking at health disparities," says Richard M. Suzman, Ph.D., Associate NIA Director, Behavioral and Social Research Program. "We knew that education was one of the most important contributors to health and life expectancy, but were not sure exactly why. These analyses give us hope that we can define strategies to help improve the health of people with less education, using interventions for illnesses that require adherence to complex regimens."
The study evaluated treatment and health status for two diseases: HIV and diabetes. These conditions were selected by the researchers because treatments are complex but highly effective in maintaining or improving health. National studies on the two diseases provide a wealth of information for characterizing people with the diseases, the details of their treatment, and results of the treatment. HIV data were obtained from the HIV Cost and Services Utilization Study (HCSUS), which followed patients receiving highly active antiretroviral therapy, or HAART. Data on diabetes came from the national Health and Retirement Study (HRS) and the Diabetes Control and Complications Trial (DCCT), a clinical trial looking at the effectiveness of diabetes treatments.
For both diseases, Goldman and Smith found, there were large differences in adherence to treatment regimens by education and that differences in complying with treatment significantly affected overall health status. The HAART data on HIV showed, for example, that 57 percent of college graduates always stuck with their treatment plan, while only 37 percent of high school dropouts did so. The study showed that income did not appear to affect adhering to treatment, while education level consistently mattered. Further analysis demonstrated that complete adherence to treatment was the single most important factor in improving health outcomes and that the role of education made a difference only in affecting adherence.
The study of people with diabetes went a step further, comparing patient behaviors in the DCCT diabetes trial. When the researchers compared the conventional therapies with a more intensive therapeutic approach, they found that education no longer had an effect on outcome. There was little difference in health status among people in different educational groups using the more intensive, enforced treatment, showing that imposing strict adherence to a treatment regimen helped the less educated more than those with higher education.
"These analyses show that the ability to adhere to a treatment regimen, while it can be influenced by education, is the bottom line for better health," points out RAND's Goldman. "Our study suggests to health providers that not all patients are alike in their ability to adhere to and maintain complicated medical regimens. But we also demonstrate that SES effects are amenable to change with training, monitoring, and possibly other approaches."
It is important to know why education matters, since related factors like income did not appear to influence adherence to health regimens or, ultimately, health status. It may be that certain features of education itself could play a role. Higher level reasoning skills and instruction in how to obtain and process complex information, components of higher education, might help patients make judgments about symptoms and treatments. In addition, personality traits and personal habits, including those that may prove useful in schooling or which schooling could help develop, might also influence adherence to health regimens. For example, the self-discipline it takes to complete assignments may prepare people for following a doctor's orders. Greater understanding of the role that these factors play will enable development of a variety of useful interventions, Suzman suggests.
The NIA leads the Federal effort to support and conduct research on the basic, biomedical, social, and behavioral aspects of aging. The Institute's Strategic Plan to Address Health Disparities specifically addresses how health disparities among various groups can be narrowed as the population ages, as research attempts to explain and understand why differences occur. To see the Strategic Plan and other information on aging, visit the NIA website at www.nia.nih.gov. Copies of NIA policy and consumer publications can be viewed online or may be obtained by calling toll free 1-800-222-2225 or TTY 1-800-222-4225.
Journal
Proceedings of the National Academy of Sciences