Predictors and Prognostic Significance of Persistent Fluid Overload: a Longitudinal Study in Chinese Peritoneal Dialysis Patients

Abstract Background: Cross-sectional studies showed that fluid overload (FO) measured by bioimpedance spectroscopy (BIS) predicted adverse outcomes in patients on peritoneal dialysis (PD). We describe the longitudinal change in volume status in Chinese PD patients, and determine its relation with clinical outcomes.Methods: We performed a single-center, retrospective analysis of all PD patients who underwent repeated BIS from 2010 to 2015. FO was defined by relative hydration index (RHI; volume of overhydration adjusted by extracellular water >7%). Variability of volume status (VVS) was denoted by the standard deviation of all RHI. The association of time-averaged RHI and VVS on patient and technique survival was explored by a competing risk model.Results: A total of 269 patients were followed for a median of 47.1 months. Multivariate mixed linear regression revealed that RHI was significantly associated with time-varying systolic blood pressure, and inversely with time-varying albumin level, lean tissue index and fat tissue index (P <0.0001 for all). Patients without FO at baseline, as compared with those who had FO, showed significantly more fluid accumulation with time (adjusted between-group mean difference in RHI: 3.2% per year, 95% confidence interval [CI] 1.5 to 4.9%, P =0.0002). Time-averaged RHI independently predicted patient survival (subdistribution hazard ratio [SHR] 1.05, 95% CI 1.03-1.08, P <0.0001) and technique survival (SHR 1.04, 95% CI 1.01-1.06, P =0.001), whereas VVS did not.Conclusions: Persistent FO was a strong predictor of patient and technique failure. Repeated bioimpedance measurements for the monitoring of volume status provided additional prognostic information in PD patients.