Rate of decline of residual renal function in patients on continuous peritoneal dialysis and factors affecting it

Objective: We analyzed residual renal function (RRF) in a large number of n ew peritoneal dialysis (PD) patients to prospectively define the time cours e of decline of RRF and to evaluate the risk factors assumed to be associat ed with faster decline. Study Design: Single-center, prospective cohort study. Setting: Home PD unit of a tertiary care University Hospital. Patients: The study included 242 patients starting continuous PD between Ja nuary 1994 and December 1997, with a minimum follow-up of 6 months and at l east three measurements of RRF. Measurement: All patients had data on demographic and laboratory variables, episodes of peritonitis and the use of aminoglycoside (AG) antibiotics, te mporary hemodialysis, and number of radiocontrast studies. Adequacy of PD w as measured from 24-hour urine and dialysate collection and peritoneal equi libration test using standard methodology. Further data on RRF was collecte d every 3 to 4 months until the patient became anuric (urine volume < 100 m L/day or creatinine clearance < 1.0 mL/min) or until the end of study in De cember 1998. Outcome Measure: The slope of the decline of residual glomerular filtration rate (GFR) tan average of renal urea and creatinine clearance) was the mai n outcome measure. Risk factors associated with faster decline were evaluat ed by a comparative analysis between patients in the highest and the lowest quartiles of the slopes of GFR, and a multivariate analysis using a stepwi se option within linear regression and general linear models. Results: There was a gradual deterioration of residual GFR with time on PD, with 40% of patients developing anuria at a mean of 20 months after the in itiation of PD. On multivariate analysis, use of a larger volume of dialysa te (p = 0.0001), higher rate of peritonitis (p = 0.0005), higher use of AG (p = 0.0006), presence of diabetes mellitus (p = 0.005), larger body mass i ndex (BMI) (p = 0.01), and no use of antihypertensive medications (p = 0.04 ) independently predicted the steep slope of residual GFR. Male gender, hig her grades of left ventricular dysfunction, and higher 24-hour proteinuria were associated with faster decline on univariate analysis only. Conclusion: Faster decline of residual GFR corresponds with male gender, la rge BMI, presence of diabetes mellitus, higher grades of congestive heart f ailure, and higher 24-hour proteinuria. Higher rate of peritonitis and use of AG for the treatment of peritonitis is also associated independently wit h faster decline of residual GFR. Whether the type of PD (CAPD vs CCPD/NIPD ) is associated with faster decline of residual GFR remains speculative.