F. Curtin et al., BODY-MASS INDEX COMPARED TO DUAL-ENERGY X-RAY ABSORPTIOMETRY - EVIDENCE FOR A SPECTRUM BIAS, Journal of clinical epidemiology, 50(7), 1997, pp. 837-843
The objective of this study was to evaluate the accuracy of body mass
index (BMI) in the diagnosis of obesity. The relationship of this weig
ht-for-height index to body composition was determined using dual-ener
gy x-ray absorptiometry (DEXA) in 226 Caucasian subjects. BMI-obesity
was defined as a BMI greater than 27.8 kg/m(2) in males and greater th
an 21.3 kg/m(2) in females. BMI-obesity was weakly sensitive (males: 1
2.5%, females 13.6%) compared with diagnosis by DEXA, defined as perce
nt body fat mass (%BF) greater than 20% in males and greater than 25%
in females Conversely, the specificity of BMI-obesity was high (males
and females: 100%). When analyzing subgroups of subjects according to
weight, sensitivity was higher among heavier subjects than among light
er ones. In both sexes and in all subgroups, the specificity was 100%.
The clinical implication of this spectrum bias is that, in men or wom
en weighing less than 80 kg, measures of obesity other than BMI, such
as bioelectrical impedance, should be preferred. (C) 1997 Elsevier Sci
ence Inc.