The relative importance of residual renal function compared with peritoneal clearance for patient survival and quality of life: an analysis of the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD )-2

BACKGROUND: The guidelines from the US National Kidney Foundation Dialysis Outcomes Quality Initiative on peritoneal dialysis (PD) assume equivalence between the peritoneal and the renal solute clearance. The authors examined in a prospective cohort study of incident dialysis patients the relative contribution of residual renal function and peritoneal clearance to patient survival and quality of life (QoL). METHODS: The authors analyzed the longitudinal data on residual renal function, clearance by dialysis, and QoL of those patients who were treated with PD 3 months after the start of dialysis and participated in a prospective multicenter study in the Netherlands (n = 413). RESULTS: The mean age was 52 years, the mean residual glomerular filtration rate (rGFR) at 3 months was 4.1 mL/min/1.73 m2 (SD: 2.7), and the mean peritoneal creatinine clearance (pCrCl) at 3 months was 4.1 mL/min/1.73 m2 (SD: 1.1). The 2-year survival was 84%. For each mL/min/1.73 m2 increase in rGFR, a 12% reduction in mortality rate was found (relative risk of death [RR] = 0.88, P = 0.039). In contrast, no significant effect of pCrCl on patient survival was established (RR = 0.91, P = 0.47). The differential impact of rGFR and pCrCl was confirmed in an analysis on combined patient and technique survival and in an analysis on a number of generic and disease-specific dimensions of QoL. CONCLUSION: The beneficial effect of renal clearance and the absence of an effect of peritoneal clearance in the range of values common in current practice on patient outcome indicate that the 2 components of total solute clearance should not be regarded as equivalent. Higher peritoneal clearance targets do not necessarily improve patient outcome