Assessment of body composition by dual energy X-ray absorptiometry, skinfold thickness and creatinine kinetics in chronic kidney disease patients

Background. Finding a method that can be routinely used to assess body composition with minimum error is still a challenge for those who work with chronic kidney disease (CKD) patients. This study aimed to compare the value of two surrogate techniques, skinfold thickness (SKF) and creatinine kinetics (CK) with dual energy X-ray absorptiometry (DEXA) as the reference method for measuring body fat and fat-free mass in non-dialysed CKD patients. Methods. The body fat and fat-free mass of 50 nondialysed CKD patients (38 male, 12 female) were measured by DEXA and compared with measurements obtained by SKF and CK. Results. The mean values of body fat and fat-free mass obtained by SKF and CK differed significantly from measurements made by DEXA. The intra-class correlation coefficient (r) for body fat between SKF and DEXA (r=0.74) and between CK and DEXA (r = 0.47) indicated a moderate degree of reproducibility. A Bland and Altman plot analysis showed a better agreement between SKF and DEXA [5.8 +/- 3.9% (-2.0 to 13.6)] than between CK and DEXA [8.8 +/- 8.8% (-8.8 to 26.4)]. Regarding fat-free mass, the intra-class correlation coefficient (r) between SKF and DEXA (r=0.85) indicated a good degree of reproducibility, while that between SKF and CK (r=0.57) indicated a moderate degree of reproducibility. The Bland and Altman plot analysis for fat-free mass showed that DEXA agreed better with SKF [-3.1 +/- 3.4kg (-9.9 to 3.7)] than with CK [-5.5 +/- 6.4 kg (-18.2 to 7.3)]. Conclusion. Skinfold thickness seems to be the method of choice for evaluating body fat. The limitations inherent to DEXA in evaluating fat-free mass makes it difficult to designate an alternate method of choice for assessing this body compartment.