Obesity adversely affects a large array of health outcomes, including coronary heart disease (CHD), other cardiovascular disease (CVD), and diabetes mellitus, according to background information in the article. Obesity is also associated with established cardiovascular risk factors, particularly diabetes and elevated levels of blood pressure and serum cholesterol. However, controversies persist as to whether excess weight has additional impact on CVD outcomes beyond its effects on established risk factors. Direct evidence on this issue is limited. In clinical settings, patients sometimes ask if they still need to control their weight if their blood pressure and cholesterol levels are not high. Therefore, in light of the worsening obesity epidemic, further research is warranted to examine whether obesity carries additional risks in the absence or presence of other major risk factors.
Lijing L. Yan, Ph.D., M.P.H., of the Feinberg School of Medicine, Northwestern University, Chicago, and Peking University, China, and colleagues examined the relationship of body mass index (BMI) earlier in life with illness and death outcomes in older age, i.e., 65 years and older, among individuals without and with other major risk factors at baseline. The Chicago Heart Association Detection Project in Industry study included 17,643 men and women aged 31 through 64 years, who were free of CHD, diabetes, or major electrocardiographic abnormalities at baseline (1967-1973). Cardiovascular risk was classified as low: systolic blood pressure 120 or less and diastolic blood pressure 80 mm Hg or less, serum total cholesterol level less than 200 mg/dL, and not currently smoking; moderate risk: nonsmoking and systolic blood pressure 121-139 mm Hg, diastolic blood pressure 81-89 mm Hg, and/or total cholesterol level 200-239 mg/dL; or having any 1, any 2, or all 3 of the following risk factors: blood pressure 140 or greater/90 mm Hg, total cholesterol level 240 mg/dL or greater, and current cigarette smoking. Body mass index was classified as normal weight (18.5-24.9), overweight (25.0-29.9), or obese (30 or greater). Average follow-up was 32 years.
In multivariable analyses that included adjustment for systolic blood pressure and total cholesterol level, the researchers found that the risk for CHD death for obese participants, compared with those of normal weight in the same risk category, was 43 percent higher for the low risk group and nearly 2.1 times higher for the moderate risk group. Compared to those of normal weight, obese individuals in the low risk group had a 4.2 times higher risk for CHD hospitalization; for the moderate risk obese group, the risk of CHD hospitalization was twice as high. Results were similar for other risk groups and for cardiovascular disease, but stronger for diabetes (low risk, 11 times increased risk for death and 7.8 times increased risk for hospitalization).
"In this predominantly white cohort who survived to age 65 years and older, persons who were overweight, and particularly those who were obese earlier in life (aged 31-64 years), had significantly higher risks of hospitalization and mortality in older age compared with persons of normal weight with similar other cardiovascular risk factors at baseline. Elevated risk was present for individuals both with and without other major cardiovascular risk factors (smoking, high blood pressure, and/or serum total cholesterol level) in young adulthood and middle age," the authors write. "In general, relationships were qualitatively consistent for both sexes for both hospitalization for and mortality from CHD, CVD, and diabetes in older age."
"Convincing evidence from our findings and other studies provides strong support for population-wide, multifaceted, primary prevention starting at young age of all major risk factors, including overweight and obesity, as a key element for the national effort to continue the progress already achieved toward ending the epidemic of CHD and CVD. The success of smoking cessation campaigns and national blood pressure and cholesterol programs can be used as models to combat and reverse the worsening obesity epidemic. The real challenge is to apply the extensive knowledge already gained in the practice of medical care and public health for the benefit of individuals and society," the researchers conclude.
(JAMA. 2006;295:190-198. Available pre-embargo to the media at www.jamamedia.org)
Editor's Note: Funding for this study was provided by grants from the National Heart, Lung, and Blood Institute.