White middle-aged Americans are not as healthy as their English counterparts, and in both countries lower income and education levels are associated with poorer health, according to a new comparison of key American and English health surveys. The healthiest Americans in the study--those in the highest income and education levels--had rates of diabetes and heart disease similar to the least healthy in England--those in the lowest income and education levels there. The research was supported by the National Institute on Aging (NIA), part of the National Institutes of Health in the U.S. Department of Health and Human Services, and British government agencies.
James Smith, Ph.D., of the RAND Corporation, Zoe Oldfield, M.Sc., of the University of London, and Sir Michael Marmot, M.D., and James Banks, Ph.D., both of University College, London, reported the comparison in the May 3, 2006, issue of the Journal of the American Medical Association.
"This comparison raises some important questions about the relationship among health, education and income in both countries," says Richard J. Hodes, M.D., director of NIA. "As many nations try to address the challenges of population aging, it will be critical to know why these differences in health status appear."
Smith and colleagues chose comparable representative samples of people ages 55 to 64 from two large, national health surveys--4,386 from the U.S. Health and Retirement Study and 3,681 from the English Longitudinal Study of Aging. Each sample was divided into three socioeconomic groups based on education and income. Both samples were limited to non-Hispanic white populations, allowing the researchers to control for special issues in different racial/ethnic communities in both countries.
"This study challenges the theory that the greater heterogeneity of the U.S. population is the major reason the United States is behind other industrialized nations in some important health measures," says Richard M. Suzman, director of NIA's Behavioral and Social Research Program. "By focusing on the comparable white populations, this study still finds the U.S. lagging."
Comparing self-reports of chronic diseases such as diabetes and heart disease between the two countries, the researchers found that Americans reported significantly higher levels of disease than the English. For example, the prevalence of diabetes in the age group was twice as high in Americans as in the English. Also, the lowest income and education group in each country reported the most cases of diabetes, hypertension, heart disease, heart attacks, strokes and chronic lung disease, while the highest income and education groups reported the least. The only disease for which this inverse relationship was not true was cancer. Smith and colleagues also found that differences between the two countries in smoking, obesity and alcohol use explained little of the difference.
Because self-reporting of diseases may have differed between the two countries, the researchers expanded their study groups to include samples of similar age groups from the National Health and Nutrition Examination Survey in the United States and the Health Survey for England. Both of these surveys include clinical measurements of risk for heart disease and stroke, including C-reactive protein, fibrinogen and HDL (high-density lipoprotein) cholesterol tests and clinical examination. These measurements confirmed the differences in diabetes and hypertension prevalence between the two countries. The differences in health status by income and education levels also persisted.
Smith, Marmot and colleagues point out that the differences exist despite greater American health care expenditures, similar patterns in life expectancy between the two countries, and the fact that smoking behavior in the two countries is similar. The authors suggest some possible areas for further consideration and study. For example, other research suggests that different experiences with disease in childhood could account for some observed differences in adult disease. Also, the researchers noted, social programs in Great Britain might help protect those who are sick from loss of income and poverty, and the lack of such programs in the United States may explain the greater association between health and wealth for Americans found in studies by Smith and others. Further, extending the study to other countries with different health systems, such as Canada and the rest of Europe, and looking at minorities would allow experts to compare the effects of publicly funded health care in each country.
The National Institute on Aging leads the federal effort supporting and conducting research on aging and the medical, social, and behavioral issues of older people. For more information on research and aging, go to http://www.nia.nih.gov.
The National Institutes of Health (NIH) -- the nation's medical research agency -- includes 27 institutes and centers and is a component of the U. S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.
Reference: James Banks, Michael Marmot, Zoe Oldfield, and James P. Smith "Disease and Disadvantage in the United States and in England," Journal of the American Medical Association (JAMA) May 3, 2006. Vol. 295, No. 16.
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