Milionis and colleagues' interesting data nicely complement our study results,1 and emphasize that excess weight is an important modifiable risk factor for stroke. In their study, a body mass index (BMI) of 27 or greater was associated with a 24% increase in the risk of nonembolic ischemic stroke in the elderly compared with a BMI of less than 27.
When we used a BMI cut point of 27 or greater in our cohort, the effect of excess weight on ischemic stroke tended to be greater in younger than in older people. Among men who were younger than 70 years at baseline in 1982, for BMIs of 27 or greater, the age-adjusted relative risk was 1.57 (95% confidence interval, 1.28-1.92) compared with participants with BMIs less than 27. Interestingly, when we restricted our analyses to participants 70 years and older at baseline and used the BMI categorization of Milionis et al, our risk estimates were quite similar: after 12.5 years of follow-up, men with BMIs of 27 or greater had an age-adjusted 24% increase (relative risk, 1.24 [95% confidence interval, 0.82-1.88]) in the risk of ischemic stroke compared with participants with BMIs less than 27. Since our cohort included mainly middle-aged men, power was low for this age group. Additional adjustment for alcohol consumption, smoking, exercise, hypertension, diabetes, history of high cholesterol, history of angina, parental history of premature myocardial infarction, and randomized treatment assignment did not attenuate this estimate (relative risk, 1.24 [95% confidence interval, 0.80-1.92]). It is not entirely surprising that the effect estimate is somewhat smaller in the elderly because individuals with high BMIs have greater risks of cardiovascular events at a younger age and thus may die earlier.2 Those who survive may be less susceptible to those events. In addition, the elderly have higher baseline risks of stroke and relative risks of even modest to moderate magnitude can translate into substantial differences in absolute risk.