Preferred clinical measures of central obesity for predicting mortality

Abstract

Objective: To define the clinical measures of obesity that best predict all cause mortality and cardiovascular disease (CVD) mortality. Design and Setting: Eleven-year mortality follow-up of an Australian urban population sample of 9309 adults aged 20-69 years in 1989. Baseline measures of obesity included body mass index (BMI), waist circumference (WC), waist-to-stature ratio and the waist-to-hip ratio. The age-standardized hazard ratios for mortality were calculated for 1 s.d. above the mean for each measure of obesity using Cox regression analysis. We constructed receiver operator characteristic (ROC) curves to assess sensitivity and specificity of the measures and to identify approximate cut-points for the prediction of risk. Results: Waist-to-hip ratio was superior by magnitude and significance in predicting all cause mortality (male hazard ratio 1.25, P=0.003, female hazard ratio 1.24, P=0.003) and CVD mortality (male hazard ratio 1.62, P<0.001, female hazard ratio 1.59, P<0.001). Waist-to-stature ratio and WC were highly significant but less powerful predictors for CVD mortality. ROC analysis showed higher 'area under the curve' values for waist-related measures in males, with similar less marked trends in females. The ROC cut-points yielded values that corresponded to current promulgated criteria. Conclusions: The waist-to-hip ratio is the preferred clinical measure of obesity for predicting all cause and CVD mortality. WC is a practical alternative. Waist-to-stature ratio is not more useful than WC alone.