Validation of bioelectrical impedance analysis for assessing dry weight of dialysis patients in Pakistan

Abstract

Accurate dry weight estimation (DW) to achieve euvolemia is one of the key objectives of hemodialysis (HD). While conventionally DW is estimated by clinical examination, bioelectrical impedance analysis (BIA) has been proposed as an objective method to determine DW and has been tested extensively in the Western population. We aim to validate BIA for determining DW in a Pakistani population against the conventional clinician's method. This is a single-center validation study conducted at two outpatient HD units of Aga Khan Hospital, Karachi. One hundred and forty-eight DW readings of patients who were on maintenance HD were taken both by BIA technology and by clinical assessment. The clinician was blinded to readings obtained by BIA. Data analysis was carried out using the Statistical Package for Social Sciences (SPSS) version 19. Median age of patients was 63 years (range 12-89). Nearly 54.1% of the samples were female (n = 80). Spearman's correlation between the clinician's estimate and BIA-derived DW showed a correlation coefficient of 0.982, which was statistically significant (P <0.001). This association remained significant when stratified analysis was carried out by dividing the sample into subgroups according to age, gender, body mass index, and total body water content. Inter-rater reliability analysis using the kappa statistics showed almost perfect agreement between the two methods, κ = 0.929 (95% confidence interval, 0.878-0.980, P <0.001). BIA has been validated as a tool for DW assessment of HD patients in Pakistan in comparison to clinical method.