Correlation between skinfold thickness and bioelectrical impedance analysis for the evaluation of body composition in patients on dialysis.

Introduction: Patients on dialysis have important changes in body composition.

Objectives: To determine the correlation between skinfold thickness (SKF) and bioimpedance analysis (BIA) for estimating fat mass (FM) and lean body mass (LBM) in patients undergoing hemodialysis (HD) and peritoneal dialysis (PD).

Methods: Cross-sectional study. We included 50 patients under dialysis treatment. To measure SKF, we used the Lange® skinfold caliper (Beta Technology, California, USA) and we carried out the impedance analysis with the Bodystat Quadscan 4000® (Quadscan, Isle of Man, UK). The measurements were performed post-hemodialysis. The PD patients were measured with and without peritoneal dialysate and body weight was corrected for peritoneal fluid. We determined the Pearson's correlation coefficient between SKF and BIA for estimating FM and LBM. We also evaluated the influence of age, sex, diuretic use, dialysis vintage, extracellular water (ECW), and intracellular water (ICW) through a multivariate regression analysis.

Results: Of the 50-patient total, 29 were men (58%) and patient mean age was 46.3 ± 16.5 years. The correlation between SKF and BIA was r = 0.784 (p < 0.001) for FM and r = 0.925 (p < 0.001) for LBM. Age and sex influenced the variability of FM, whereas sex, age, and ECW influenced the variability of LBM, both evaluated through the SKF and BIA methods.

Conclusion: SKF and BIA are useful methods in clinical practice. The strong and statistically significant correlations between the two methods show they are interchangeable. Age, sex, ECW, and ICW influence the variability of FM and LBM.