The influence of demographic factors and modality on loss of residual renal function in incident peritoneal dialysis patients

◆ Objective: To determine whether gender, race, diabetes, peritoneal dialysis (PD) modality, and comorbid conditions influence loss of residual renal function (RRF). ◆ Design: Retrospective study of incident PD patients, using database of prospectively collected demographic, laboratory, and clearance data. ◆ Setting: Peritoneal Dialysis Registry of the University of Pittsburgh Medical Center. ◆ Patients: The study included 184 continuous ambulatory PD and automated PD patients who had at least two 24-hour urine collections for glomerular filtration rate (GRF) between April 1991 and March 2000. 836 urine collections were analyzed. ◆ Outcome Measures: Loss of RRF was defined as the slope of the decline in GFR as measured by the average of creatinine and urea clearances in 24-hour urine collections. Stepwise forward regression was used to identify demographic and laboratory factors associated with loss of GFR. Spearman correlations were used to assess the significance of associations. ◆ Results: The median rate of decline of renal function was -0.17 mL/minute/month. Gender, race, diabetes, automated PD, peritoneal equilibration test, protein equivalent of nonprotein nitrogen appearance normalized to body surface area, and serum albumin did not predict loss of RRF. Cardiac disease was the only variable affecting decline of RRF (p=0.045). ◆ Conclusion: Modality of PD and patient demographic factors do not contribute to the rate at which RRF is lost in incident PD patients. Additional study of the factors contributing to the decline and maintenance of RRF is needed.