[Cut-off values of waist circumference for central obesity in Chinese adults]

To investigate the appropriate cut-off values of waist circumference(WC)for central obesity and severe central obesity in Chinese adults.

A total of 10 265 participants aged 35-69 years from the cross-sectional survey of the PRC-USA Collaborative Study of Cardiovascular and Cardiopulmonary Epidemiology between 1993 and 1994 with integral data were included. Each integer unit in centimeters of WC in a given range was used as the cut-off point to detect clustering of risk factors, which was defined as an individual with 2 or more risk factors including hypertension, diabetes, hypercholesterolemia, hypertriglyceridemia and low levels of high-density lipoprotein cholesterol. Sensitivity, specificity and distance from the receiver operating characteristic (ROC) curves to the upper left corner of the ROC graph were calculated. The WC value corresponding to the point on the ROC curve nearest to the upper left corner was considered as the optimal cut-off value for central obesity and the value corresponding to the point with specificity of 90% or more was considered as the optimal cut-off for severe central obesity.

The mean WC was (80.5 ± 9.9) cm in men and (77.8 ± 10.0) cm in women; 18.1% (890/4 921) of men and 14.5% (776/5 344) of women were identified with two or more major risk factors. Based on the ROC curve analysis, the optimal value of WC to detect clustering of risk factors was ≥ 84 cm for men and ≥ 80 cm for women, and the shortest distance to the upper left corner was 0.430 and 0.450, respectively. The cut-off values of WC to detect clustering of risk factors with specificity of 90% or more were ≥ 93 cm and ≥ 91 cm for men and women, respectively.

The cut-off points of WC for central obesity and severe central obesity in Chinese adults obtained from this study are equal or similar to the WC cut-off values proposed by the Guidelines for Prevention and Control of Overweight and Obesity in Chinese Adults.