Does the adverse effect of excess body weight on cardiovascular disease decline with age?
Excess body weight increases CVD risk but some studies suggest that this effect declines with age. We addressed this question using >40 years of data from The Framingham Study. In general, we found that the incidence of CVD increased with advancing age and BMI. To evaluate the age-specific effects of BMI on CVD risk, we used two types of estimates--rate ratios (RR) and rate differences (RD). After adjusting for potential confounding by age, sex, education, activity, smoking, and alcohol, the RR of CVD associated with obesity (BMI ≥30 vs. BMI <22) generally declined with age (RR=2.2, 2.4, 1.8, 1.5, and 1.4, for those in their 30s, 40s, 50s, 60s, and 70s, respectively). The RR associated with moderate overweight (BMI 26-29 vs. BMI <22) also declined with age, ranging from a RR of 1.8 (95% CI: 1.4-2.3) for the youngest subjects to a slight protective effect (RR=0.93, 95% CI: 0.71-1.2) in the oldest. The RD represents the number of excess cases of CVD attributable to a given body weight. Among the obese, the RD did not decline with age (with 12.0, 15.6, 13.7, 12.7, and 16.9 excess cases of CVD/1000 person-years in the respective age categories). Thus, the excess risk of CVD attributable to obesity (BMI ≥30) was constant across five decades of adult life. In contrast, more modest amounts of overweight were not associated with an excess risk of CVD among men and women over the age of 60.⇓