Independent Effects of Renal and Peritoneal Clearances on the Mortality of Peritoneal Dialysis Patients

Abstract

Previous studies show that peritoneal Kt/V is an independent predictor of survival in anuric patients receiving continuous ambulatory peritoneal dialysis (CAPD). We studied whether peritoneal Kt/V has the same effect in CAPD patients with residual renal function. Observational cohort study. Single dialysis center in a university teaching hospital. New and prevalent CAPD patients. We examined the 5-year follow-up results of our prospective study previously reported (Kidney Int 2000; 58:400-7). A total of 270 CAPD patients were followed for up to 6 years. Dialysis adequacy indices, residual renal function, and nutritional data were monitored. Primary outcomes included mortality and technique failure. Peritoneal Kt/V rather than total Kt/V was used for multivariate survival analysis. Average duration of follow-up was 35.1 +/- 22.0 months. Average peritoneal Kt/V throughout the study was 1.59 +/- 0.37; median residual glomerular filtration rate (GFR) 0.82 mL/minute. Five-year actuarial patient survival was 41.5%, and technique survival was 23.1%. Multivariate analysis showed that sex, age, duration of dialysis, presence of diabetes, serum albumin, dialysate-to-plasma creatinine ratio at 24 hours, peritoneal Kt/V, residual GFR, and normalized protein nitrogen appearance were independent factors of both actuarial patient survival and technique survival. For every 0.1 unit higher peritoneal Kt/V, relative mortality risk was 0.94 (95% Cl 0.89 - 0.99, p = 0.03). When prevalent and new CAPD cases were analyzed separately, peritoneal Kt/V predicted survival only for prevalent CAPD patients. We conclude that, in prevalent CAPD patients with relatively low levels of peritoneal clearance and residual renal function, a higher peritoneal Kt/V is associated with better survival. Peritoneal clearance below 1.6-1.7 likely has a major detrimental effect on the clinical outcome of CAPD patients with little residual renal function.