Validating Body Fat Assessment by Bioelectric Impedance Spectroscopy in Taiwanese Hemodialysis Patients.

OBJECTIVE Obesity is becoming increasingly common in hemodialysis (HD) patients and is associated with inflammation and increased mortality. The primary aim of the present study was to evaluate the accuracy and variability of the bioimpedance device in measuring body fat in Taiwanese dialysis patients. DESIGN Cross-sectional study. SUBJECTS One hundred twenty-two adult patients receiving HD in a single hospital in Taiwan. SETTING We compared the results of fat mass (FM) measured by dual-energy x-ray absorptiometry (DEXA) and bioelectrical impedance spectroscopy device (Body composition monitor, BCM). MAIN OUTCOME MEASUREMENT FM measured by BCM was calculated by subtracting fat-free mass (FFM) from body mass assuming fractional hydration of FFM of 0.73 or the proprietary prediction equations from the BCM model. RESULTS Assessment of whole-body composition showed that percentage FM measured using the 2 techniques was highly correlated when using the BCM model or estimating from total body water using constant (0.73) hydration (r = 0.87, P < .001). There was no evident difference in measurement between patients gender. The Bland-Altman plot also showed good agreement of percentage of FM (t = 3.82; P < .001). In female patients, it was found that BCM significantly underestimated mean FM as compared to DEXA. However, the mean differences of the estimates between the methods were small (0.35 ± 3.00 kg) and with Bland-Altman plot the limits of agreements were -5.5 to 6.2 kg (P = .40) for FM in female patients. CONCLUSIONS Using DEXA as the reference test, BCM is a valid tool for the assessment of total body fat in HD patients. Hence, it may provide a more accessible tool for early detection of changes in body composition in these high-risk patients.