Background: Residual glomerular filtration rate (GFR) is a much more important determinant of survival in peritoneal dialysis patients, than peritoneal solute clearances. However, anuric peritoneal dialysis patients are solely dependent on peritoneal solute clearances. The aim of the study was to analyze the effects of peritoneal small solute clearances and ultrafiltration on survival in anuric patients, and to establish the minimum levels of small solute clearances and net ultrafiltration. These objectives were investigated in a prospective cohort study in incident peritoneal dialysis patients who had become anuric during follow-up.
Methods: The Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD) is a prospective multicenter cohort study in which new adult dialysis patients are included and followed during 6 months intervals. Included were 542 peritoneal dialysis patients. Of these, 166 developed anuria, 130 of which could be included in the study.
Results: Two-year patient survival after the outset of anuria was 67%, technique survival 73%, and the combined 2-year patient and technique survival was 50%. Risk factors associated with mortality were age, comorbidity, the duration of peritoneal dialysis before anuria, and a low serum albumin. Peritoneal solute clearances were analyzed time-dependently. These parameters were not associated with survival when analyzed as continuous variables and also not when the analyses were done in quintiles, although the time-dependent approach was almost significant for Kt/V(urea). On the other hand, when the results were analyzed dichotomously using predefined cutoff points, Kt/V(urea) <1.5 per week and creatinine clearance <40 L/week/1.73 m2 were associated with an increase in the relative risk of death. Also peritoneal ultrafiltration was significantly associated with survival.
Conclusion: The survival of anuric peritoneal dialysis patients is in line with expectations based on the duration of dialysis. The risk factors for death are the same as in the dialysis population as a whole. Besides an association with ultrafiltration, our study enabled us to define the lower limits of adequate peritoneal dialysis, that is Kt/V(urea) <1.5 per week and creatinine clearance <40 L/week/1.73 m2.