Predictors of Decline of Residual Renal Function in New Peritoneal Dialysis Patients

Abstract

The aim of this study was to prospectively evaluate the risk factors for decline of residual renal function (RRF) in an incident peritoneal dialysis (PD) population. Prospective observational study of an incident PD cohort at a single center. Tertiary-care institutional dialysis center. The study included 146 consecutive patients commencing PD at the Princess Alexandra Hospital between 1 August 1995 and 1 July 2001 (mean age 54.8 +/- 1.4 years, 42% male, 34% diabetic). Patients with failed renal transplants (n = 26) were excluded. Timed urine collections (n = 642) were performed initially and at 6-month intervals thereafter to measure RRF. The development of anuria was also prospectively recorded. The mean (+/- SD) follow-up period was 20.5 +/- 14.8 months. The median slope of RRF decline was -0.05 mL/minute/month/1.73 m2. Using binary logistic regression, it was shown that the 50% of patients with more rapid RRF loss (< -0.05 mL/min/month/1.73 m2) were more likely to have had a higher initial RRF at commencement of PD [adjusted odds ratio (AOR) 1.83, 95% confidence interval (CI) 1.39-2.40] and a higher baseline dialysate/ plasma creatinine ratio at 4 hours (D/P creat; AOR 44.6, 95% CI 1.05-1900). On multivariate Cox proportional hazards model analysis, time from commencement of PD to development of anuria was independently predicted by baseline RRF [adjusted hazard ratio (HR) 0.81, 95% CI 0.60-0.81], D/P creat (HR 2.87, 95% CI 2.06-82.3), body surface area (HR 6.23, 95% CI 1.53-25.5), dietary protein intake (HR 2.87, 95% CI 1.06-7.78), and diabetes mellitus (HR 1.65, 95% CI 1.00-2.72). Decline of RRF was independent of age, gender, dialysis modality, urgency of initiation of dialysis, smoking, vascular disease, blood pressure, medications (including angiotensin-converting enzyme inhibitors), duration of follow-up, and peritonitis rate. The results of this study suggest that high baseline RRF and high D/P creat ratio are risk factors for rapid loss of RRF. Moreover, a shorter time to the onset of anuria is independently predicted by low baseline RRF, increased body surface area, high dietary protein intake, and diabetes mellitus. Such at-risk patients should be closely monitored for early signs of inadequate dialysis.