Application of Bioimpedance Spectroscopy in Asian Dialysis Patients (ABISAD): serial follow-up and dry weight evaluation

BACKGROUND Maintenance of the optimal fluid status in hemodialysis patients is still a challenging task in daily clinical practice. A bioelectric impedance technique has been applied for evaluation of hydration status in the dialysis population in recent years, but serial observations of its role in clinical dry weight determination are lacking. In this study, serial follow-up data of a body composition monitor based on bioimpedance spectroscopy (BCM-BIS) applied in dialysis patients were analyzed to define the technique's feasibility, precision and possible role in dry weight determination. METHODS BCM-BIS was applied monthly to 194 hemodialysis patients for 6 months. Intra-patient precision was analyzed. Bland-Altman analysis and repeated-measures analysis of variance (ANOVA) were used to define the relationship between the dry weights determined by BCM-BIS and by clinical judgment. RESULTS The coefficients of variation (CVs) of fluid parameters were <5%. Serial changes in dry weight differences were compared in groups with different post-dialysis hydration status and dry weight differences decreased gradually. Bland-Altman analysis revealed that the range of these differences was significantly narrower towards the latter part of the study. The upper limit of agreement with 95% confidence interval (CI) was 1.47 L and the lower limit was -3.02 L. CONCLUSIONS BCM-BIS is precise and can be easily applied in the clinical setting. Discrepancy between the dry weights determined by BCM-BIS and by clinical judgment significantly decreased during the study. It is sensitive in dry weight determination, especially for those patients with obvious over-hydration (OH) by BCM-BIS. Patients with post-dialysis OH results beyond some critical values (>1.5 L or <-3 L) should be closely monitored.