Assessment of body composition in Indian adults: comparison between dual-energy X-ray absorptiometry and isotope dilution technique

摘要

Dual-energy X-ray absorptiometry (DXA) and isotope dilution technique have been used as reference methods to validate the estimates of body composition by simple field techniques; however, very few studies have compared these two methods. We compared the estimates of body composition by DXA and isotope dilution (O-18) technique in apparently healthy Indian men and women (aged 19-70 years, n 152, 48% men) with a wide range of BMI (14-40 kg/m(2)). Isotopic enrichment was assessed by isotope ratio mass spectroscopy. The agreement between the estimates of body composition measured by the two techniques was assessed by the Bland-Altman method. The mean age and BMI were 37 (SD 15) years and 23.3 (SD 5.1) kg/m(2), respectively, for men and 37 (SD 14) years and 24.1 (SD 5.8) kg/m(2), respectively, for women. The estimates of fat-free mass were higher by about 7 (95% CI 6, 9)%, those of fat mass were lower by about 21 (95% CI -18, -23) %, and those of body fat percentage (BF%) were lower by about 7.4 (95% CI -8.2, -6.6)% as obtained by DXA compared with the isotope dilution technique. The Bland-Altman analysis showed wide limits of agreement that indicated poor agreement between the methods. The bias in the estimates of BF% was higher at the lower values of BF%. Thus, the two commonly used reference methods showed substantial differences in the estimates of body composition with wide limits of agreement. As the estimates of body composition are method-dependent, the two methods cannot be used interchangeably