A comparison of peritonitis rates from the United States Renal Data System database: CAPD versus continuous cycling peritoneal dialysis patients

Background: Previous comparisons of peritonitis rates between continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD) have produced varying results. Methods: Using United States Renal Data System data, the authors evaluated peritonitis rates in 1994 through 1997 incident CAPD (n = 9,190) and CCPD (n = 2,785) Medicare patients. Patients were characterized during a 6-month entry period (months 4 through 9) and followed for a maximum of 2 years (months 10 through 33). Medicare claims data provided the date of the first peritonitis episode during the follow-up period. The time to first peritonitis after 9 months of PD was compared by the log-rank test, and then by Cox regression with adjustment for peritoneal dialysis modality, age, sex, race, primary end-stage renal disease (ESRD) diagnosis, number of entry-period hospital days, peritonitis during the entry period, hematocrit value, and congestive heart failure. Results: For CAPD and CCPD, the adjusted average months to first peritonitis after 9 months of PD were 17.1 and 16.1, respectively. The probabilities of remaining without a peritonitis episode after 1 year of follow-up were 0.53 and 0.50, respectively (P = 0.008). The risk of peritonitis was lower for CAPD than for CCPD (relative risk, 0.939; 95% confidence interval, 0.883 to 0.998). Other significant risk factors included age ≤44 years, black race, diabetes as primary ESRD diagnosis, peritonitis during the entry period, greater than 4 entry-period hospital days, and congestive heart failure. Patients treated with recombinant human erythropoietin with a hematocrit value of ≥36% had lower risk of peritonitis. Conclusion: Compared with CCPD, CAPD is associated with a slightly but significantly lower risk for development of a first peritonitis episode after 9 months of peritoneal dialysis therapy.