Effect of duration of chronic peritoneal dialysis therapy on the development of peritonitis

Objective: Long-term chronic peritoneal dialysis (CPD) therapy has been ass ociated with alterations in peritoneal membrane structure and peritoneal ma crophage function. We thus reviewed our experience with the development of peritonitis among patients maintained on CPD therapy for various time perio ds to determine if the spectrum of organisms, rates of peritonitis, and out come changed with the duration of CPD therapy. Setting and Patients: Patients maintained on CPD therapy in our out-patient unit in New Haven, Connecticut. Design: Retrospective review of the charts of patients maintained on CPD th erapy (HomeChoice Cycler or Ultrabag, Baxter, [McGaw Park, IL, U.S.A.) betw een 1 January 1997 and 31 March 1998. These patients were divided into thre e groups: group 1, patients maintained on CPD therapy less than or equal to 12 months; group 2, patients maintained on CPD therapy for 13 - 36 months; and group 3, patients maintained on CPD therapy for greater than or equal to 37 months. Results:The study included 256 patients: 101 patients in group 1, 110 patie nts in group 2, and 45 patients in group 3. All groups of patients were sim ilar in age. There were significantly fewer Caucasians and fewer males in g roup 3 in comparison to groups 1 and 2. The incidence of diabetes mellitus, coronary artery disease, and peripheral vascular disease was significantly lower among patients in group 3 in comparison to groups 1 and 2. There wer e 155 episodes of peritonitis during the study period for an overall rate o f 1 episode in 18.7 patient-months. The overall, gram-positive, and gram-ne gative rates of peritonitis were not significantly different among the pati ents in groups 1,2, and 3. There were more episodes of Staphylococcus aureu s peritonitis among patients in group 3 in comparison to group 2 (1 episode in 59.6 vs 1 episode in 280.2 patient-months, respectively). Two weeks aft er the development of peritonitis, 94.6% of the patients in group 3 continu ed CPD therapy, while 79.4% of the patients in group 1 continued CPD therap y (p < 0.05). No patient in group 3 transferred to hemodialysis, while 10.3 % and 8.2% of the patients in groups 1 and 2 transferred to hemodialysis (p < 0.05). The death rate 2 weeks after the onset of peritonitis was 10.3%, 9.8%, and 5.4% in groups 1, 2, and 3, respectively (p = NS). Conclusions: Despite the immunological and morphological changes that occur in the peritoneal cavity with increased time on CPD therapy, there was no difference in the overall, gram-positive, or gram-negative rates of periton itis for patients maintained on CPD therapy for various time periods. Patie nts in group 3 continued CPD therapy more often than did patients in group 1. Patients in group 3 transferred to hemodialysis less often than did the remaining patients in the study period. The incidence of death was not sign ificantly different for the three groups of patients.