Predictors of Residual Renal Function Decline in Peritoneal Dialysis Patients: The balANZ Trial

♦ OBJECTIVE: Preservation of residual renal function (RRF) is associated with improved survival. The aim of the present study was to identify independent predictors of RRF and urine volume (UV) in incident peritoneal dialysis (PD) patients. ♦ METHODS: The study included incident PD patients who were balANZ trial participants. The primary and secondary outcomes were RRF and UV, respectively. Both outcomes were analyzed using mixed effects linear regression with demographic data in the first model and PD-related parameters included in a second model. ♦ RESULTS: The study included 161 patients (mean age 57.9 ± 14.1 years, 44% female, 33% diabetic, mean follow-up 19.5 ± 6.6 months). Residual renal function declined from 7.5 ± 2.9 mL/min/1.73 m² at baseline to 3.3 ± 2.8 mL/min/1.73 m² at 24 months. Better preservation of RRF was independently predicted by male gender, higher baseline RRF, higher time-varying systolic blood pressure (SBP), biocompatible (neutral pH, low glucose degradation product) PD solution, lower peritoneal ultrafiltration (UF) and lower dialysate glucose exposure. In particular, biocompatible solution resulted in 27% better RRF preservation. Each 1 L/day increase in UF was associated with 8% worse RRF preservation (p = 0.007) and each 10 g/day increase in dialysate glucose exposure was associated with 4% worse RRF preservation (p < 0.001). Residual renal function was not independently predicted by body mass index, diabetes mellitus, renin angiotensin system inhibitors, peritoneal solute transport rate, or PD modality. Similar results were observed for UV. ♦ CONCLUSIONS: Common modifiable risk factors which were consistently associated with preserved RRF and residual UV were use of biocompatible PD solutions and achievement of higher SBP, lower peritoneal UF, and lower dialysate glucose exposure over time.