RELIABILITY OF DUAL-FREQUENCY BIPEDAL BIOELECTRICAL IMPEDANCE ANALYSIS SCALES IN ESTIMATING TOTAL BODY WATER AND ‘DRY WEIGHT’ IN MAINTENANCE HEMODIALYSIS PATIENTS.

Abstract

Assessing changes in muscle mass (MM) and total body water (TBW) in HD patients is notoriously difficult. Equipment is expensive and impractical for regular use by patients having home-based dialysis. Therefore the purpose was to assess the reliability of Dual Frequency Bipedal Bioelectrical Impedance Analysis (DF-BP BIA) scales in estimating TBW and MM in maintenance HD Patients. Sixty two stable HD patients from five satellite dialysis centers had BIA measurements taken before and 20 minutes after each consecutive HD session, for two to four weeks. A subset also had Bioelectrical Impedance Spectroscopy (BIS) measures taken for comparison. Participant’s intra individual percentage coefficient of variation range for MM (Pre HD = 0.69 to 6.16; Post HD = 0.56 to 7.68) and TBW (Pre HD = 0.70 to 10.22; Post HD = 0.58 to 8.78) were wide and clinically unacceptable. Bland Altman analysis of DF-BP BIA and BIS showed a bias of - 2.1±3.2L (-8.4L to 4.2L) Pre HD; -2.9±2.0L (-6.8 to 1.1L) Post HD, for TBW with a strong correlation ( r s = 0.855 to 0.93; p<0.05). In conclusion, DF-BP BIA does not reliably estimate TBW, changes in TBW or MM in maintenance HD patients. When compared to BIS, DF-BP BIA underestimates TBW. DF-BP BIA is therefore clinically unacceptable for analysis of body composition changes in HD patients.