COMPARISON OF BODY-COMPOSITION BY DUAL-ENERGY X-RAY ABSORPTIOMETRY TOOTHER ESTIMATES OF BODY-COMPOSITION DURING WEIGHT-LOSS IN OBESE PATIENTS WITH RHEUMATOID-ARTHRITIS

Body composition was determined by dual energy X-ray absorptiometry (D XA) scanning and classical reference methods (K-40, (H2O)-H-3, and a c ombination of these in a four-compartment model) in 19 overweight pati ents with rheumatoid arthritis who underwent a 12-week weight-reducing regimen. The aim of the study was to investigate whether DXA provides a valid estimate of body composition. The results showed that weight as determined by DXA was highly significantly correlated to weight det ermined by scales. Furthermore, significant correlations were found in the body components (fat-free mass, fat mass) determined by DXA, K-40 , (H2O)-H-3 and the four-compartment model. Mean values differed sligh tly but significantly. With respect to changes in body composition, no significant correlations were found between any of the methods, excep t for the weight loss recorded by DXA and scales, and loss of fat mass (and fat free mass) estimated by (H2O)-H-3 and the four-compartment m odel. The sparseness of correlations reflected the small changes in fa t-free mass and fat mass (2.6 and 1.7 kg respectively), and the fact t hat changes were comparable to measurement errors of the various metho ds. We suggest that DXA scanning is a valid supplement for determinati on of body composition. Validation of DXA scanning requires new experi mental in vitro investigations, which, incidentally, also applies to t he classical reference methods.