Body-mass index and mortality in a prospective cohort of US adults

Background Body-mass index (the weight in kilograms divided by the square o f the height in meters) is known to be associated with overall mortality. W e investigated the effects of age, race, sex, smoking status, and history o f disease on the relation between body-mass index and mortality. Methods In a prospective study of more than 1 million adults in the United States (457,785 men and 588,369 women), 201,622 deaths occurred during 14 y ears of follow-up. We examined the relation between body-mass index and the risk of death from all causes in four subgroups categorized according to s moking status and history of disease. In healthy people who had never smoke d, we further examined whether the relation varied according to race, cause of death, or age. The relative risk was used to assess the relation betwee n mortality and body-mass index. Results The association between body-mass index and the risk of death was s ubstantially modified by smoking status and the presence of disease. In hea lthy people who had never smoked, the nadir of the curve for body-mass inde x and mortality was found at a body-mass index of 23.5 to 24.9 in men and 2 2.0 to 23.4 in women. Among subjects with the highest body-mass indexes, wh ite men and women had a relative risk of death of 2.58 and 2.00, respective ly, as compared with those with a body-mass index of 23.5 to 24.9. Black me n and women with the highest body-mass indexes had much lower risks of deat h (1.35 and 1.21), which did not differ significantly from 1.00. A high bod y-mass index was most predictive of death from cardiovascular disease, espe cially in men (relative risk, 2.90; 95 percent confidence interval, 2.37 to 3.56). Heavier men and women in all age groups had an increased risk of de ath. Conclusions The risk of death from all causes, cardiovascular disease, canc er, or other diseases increases throughout the range of moderate and severe overweight for both men and women in all age groups. The risk associated w ith a high body-mass index is greater for whites than for blacks. (N Engl J Med 1999;341:1097-105.) (C)1999, Massachusetts Medical Society.