Older adults who cannot read and understand basic health information appear to have increased mortality rates over a five-year period than those with adequate health literacy, according to a report in the July 23 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
Education, as measured by the number of years of school completed, has been linked to longer life, according to background information in the article. This may be because more education tends to result in better job opportunities, a higher annual income and access to housing, food and health insurance. "Another possible mechanism by which education could exert a direct effect on health is reading fluency," the authors write. "The number of years of school completed is strongly associated with reading fluency. As a result, individuals with more education tend to have a better capacity to obtain, process and understand basic health information and services needed to make appropriate health decisions: i.e., they have higher levels of health literacy."
David W. Baker, M.D., M.P.H., of Northwestern University Feinberg School of Medicine, Chicago, and colleagues interviewed 3,260 Medicare patients age 65 and older in four metropolitan areas in 1997, asking questions about demographics and health. Participants also completed a test of health literacy that involved two reading passages and four mathematical items. Scores range from zero to 100, with zero to 55 designating inadequate health literacy, 56 to 66 indicating marginal health literacy and 67 to 100 signifying adequate health literacy. The National Death Index was then used to identify participants who died through 2003.
Among the participants, 2,094 (64.2 percent) had adequate health literacy, 366 (11.2 percent) had marginal health literacy and 800 (24.5 percent) had inadequate health literacy. A total of 815 (25 percent) died during the average 67.8 months of follow-up, including 39.4 percent of those with inadequate health literacy, 28.7 percent of those with marginal health literacy and 18.9 percent of those with adequate health literacy. The results suggesting an increased risk of mortality associated with inadequate health literacy remained statistically significant after the researchers factored in demographics, socioeconomic status, and health behaviors at the beginning of the study. In contrast, years of school completed were only weakly associated with death during the study period.
Health literacy was most strongly associated with death from cardiovascular disease--380 (11.7 percent) of participants died of this cause during the study, including 19.3 percent of those with inadequate health literacy and 16.7 percent of those with marginal health literacy, compared with only 7.9 percent of those with adequate health literacy.
"Inadequate health literacy is associated with less knowledge of chronic disease and worse self-management skills for patients with hypertension, diabetes mellitus, asthma and heart failure," the authors write. "Use of cancer screening and vaccinations are also lower among people with inadequate health literacy. Thus, the association between health literacy and adverse health outcomes probably occurs as the result of a wide variety of pathways that have a cumulative effect."
Recent studies have suggested that it is possible to improve the health of patients with diabetes and heart failure despite their low health literacy using targeted interventions. However, a broader solution is needed, the authors note. "Most people will have many acute and chronic medical conditions during their life and face many situations in which they must make health and health care choices and decisions," they conclude. "As a result of these myriad demands placed on patients today, widespread improvements in health and health care communication will likely be necessary to reduce the association between health literacy and mortality."
(Arch Intern Med. 2007;167(14):1503-1509. Available pre-embargo to the media at www.jamamedia.org.)
Editor's Note: This study was supported by a grant from the National Institute on Aging and a Career Development Award from the Centers for Disease Control and Prevention. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
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