Even in the absence of high blood pressure and other cardiovascular risk factors, obesity in midlife is associated with an elevated risk of hospitalization and death from coronary heart disease (CHD) in older age, according to a report in the Journal of the American Medical Association.
"Our study adds one more reason to pay attention to your weight, even if your other risk factors are under control," lead author Dr. Lijing L. Yan, from Northwestern University in Chicago, told Reuters Health.
"Numerous reports have linked obesity and overweight with adverse health outcomes," Yan said, "but whether these factors act independently is still somewhat controversial. Our study is unique in that we were able to evaluate the associations over more than 30 years and because our cohort was big enough to examine the associations in more detail than ever before."
The study involved 17,643 subjects who had their body mass index (BMI), the ratio of height to weight used to determine obesity, and cardiovascular risk factors assessed in midlife (31 to 64 years of age) between 1967 and 1973. The subjects were then followed through 2002 to assess hospitalization and death from CHD, cardiovascular disease, and diabetes.
The participants were divided into five cardiovascular risk groups.
Low-risk subjects were nonsmokers with normal blood pressure and a total cholesterol level below 200 mg/dL, without taking blood pressure-lowering or lipid-lowering medications. Moderate-risk subjects were also nonsmokers who were not on medication, but had slightly elevated blood pressure and total cholesterol levels. People with 1, 2 or 3 risk factors that included high blood pressure, high cholesterol, or current smoking were defined as being at intermediate, elevated or highest risk.
The subjects were further stratified into three weight groups. A BMI of 18.5 to 24.9 was considered normal, 25.0 to 29.9 overweight, and 30 or greater as obese.
Among moderate-risk patients, obesity doubled the risk of CHD death and CHD hospitalization after age 65, compared with those of normal weight. In low-risk patients, obesity raised the risk of CHD death and CHD hospitalization by 1.43- and 4.25-fold, respectively. In both groups, the presence of obesity increased the risk of diabetes by more than 7-fold.
Being overweight was also linked to poor health outcomes, but the magnitude of the elevated risk was less than that seen with obesity, the report indicates. The relationship also held true for the other, higher cardiovascular risk categories, the investigators found.
"I was not surprised by the overall independent association between obesity and poor health outcomes," Yan said. "I was, however, a little surprised that just one BMI measurement in midlife could so strongly predict outcomes in older age."
Yan said her group is now involved in a study looking at the impact of obesity on heart failure outcomes.
SOURCE: Journal of the American Medical Association, January 11, 2006.
