Purpose: To determine whether white, black and hispanic young (17-39y) and middle-aged (40-59y) adults, and elderly (60-90y) Americans have the same values of abdominal adiposity (estimated from waist circumference (WC) at the established levels of overweight (body mass index, BMI 25-29.9 kg/m2) and obesity (BMI > or = 30 kg/m2).
Methods: Data (n=16,120) from the US Third National Health and Nutrition Survey were utilized. Age-adjusted linear regression analyses were used to estimate gender- and ethnic-specific WC values corresponding to overweight and obesity. Receiver operating characteristic (ROC) curves were also employed to determine the choices of WC values corresponding to the established BMI cut-off points. With ROC, gender- and ethnic-specific cut-off points producing the best combination of sensitivity and specificity were selected as optimal thresholds for WC values corresponding to the established BMI cut-off points.
Results: WC values associated with the established BMI were lower in blacks and hispanics compared with whites. In men, the WC values that corresponded to overweight ranged from 89 to 106 cm, from 84 to 95 cm, and from 87 to 97 cm in whites, blacks and hispanics, respectively. The corresponding values for obesity ranged from 99 to 110 cm, from 96 to 107 cm, and from 97 to 108 cm. The WC values that corresponded to overweight in women ranged from 82 to 91 cm, from 81 in to 90 cm, and from 83 to 92 cm in whites, blacks and hispanics, respectively. The analogous values for obesity ranged from 94 to 101 cm, from 93 to 100cm, and from 94 to 101 cm.
Conclusions: The lack of higher WC values in blacks (particularly women) and hispanics at the same levels of BMI for whites challenges previously held assumptions regarding the role of abdominal adiposity in cardiovascular disease experienced by non-whites. Defining the anthropometric variables that satisfactorily describe reasons for ethnic differences in cardiovascular disease is one of the challenges for future research.