BMI vs. waist circumference for identifying vascular risk.

OBJECTIVE: Current guidelines recommend measurement of both BMI and waist circumference (WC) in individuals with BMI between 25.0 and 34.9 kg/m(2). We investigated the relative contributions of BMI and WC toward identifying risk of adverse vascular events in a community-based sample. METHODS AND PROCEDURES: We evaluated Framingham Study participants (n = 4,195 person-examinations, 53% women) using pooled logistic regression to assess the incremental prognostic utility of WC in predicting risk of a first cardiovascular disease (CVD) event in the three BMI categories (normal, <25 kg/m(2); overweight, 25 to <30 kg/m(2); obese, > or =30 kg/m(2)) and to assess the incremental prognostic utility of BMI and WC separately for predicting risk of a first cardiovascular event.
RESULTS: On follow-up (16 years), 430 participants (158 women) had experienced a first CVD event. In overweight women, but not in overweight men, larger WC was found to be an independent predictor of CVD incidence, longitudinally (in women, multivariable-adjusted odds ratio (OR) per s.d. increment in WC 1.86, 95% confidence interval (CI) = 1.03-3.36, P = 0.04; in men adjusted OR per s.d. increment in WC 0.91, 95% CI 0.60-1.38, P = 0.66). In obese individuals and in those with normal BMI, WC was not associated independently with incident CVD. When BMI and WC were analyzed separately for predicting risk of a first cardiovascular event, the c statistics associated with the multivariable CVD models incorporating BMI vs. WC were nearly identical in men and women. DISCUSSION: Knowledge of WC aids identification of vascular risk among overweight women. Among normal weight or obese women and men (regardless of BMI category) WC did not appear to substantially add to prediction of risk of vascular events.