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 m(2) (SD: 2.7), and the mean peritoneal creatinine clearance (pCrCI) at 3 months was 4.1 mL/min/1.73 m(2) (SD: 1.1). The 2-year survival was 84%. For each mL/min/1.73 m(2) 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 pCrCI on patient survival was established (FIR = 0.91, P = 0.47). The differential impact of rGFR and pCrCI 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.