Early Peritonitis Within the First Six Months and One-Year Mortality in Elderly Peritoneal Dialysis Patients: A Multicentre Retrospective Study

Background and Objectives: This study aimed to determine the incidence of peritonitis developing within the first six months of therapy in peritoneal dialysis (PD) patients aged 65 years and older, and to evaluate the risk factors associated with one-year mortality. Materials and Methods: A total of 227 PD patients aged ≥65 years across nine centers were evaluated in this retrospective, multicentre cohort study. Demographic characteristics, comorbidities, laboratory parameters, and clinical outcomes were analyzed using electronic health records. Early peritonitis was defined as an episode occurring within the first six months following PD initiation. Univariate and multivariable logistic regression analyses were performed to identify predictors of one-year mortality. Results: Early peritonitis developed in 70 patients (30.8%), and the overall one-year mortality rate was 15.9% (n = 36). In univariate analysis, one-year mortality was significantly associated with underlying coronary heart disease (58.3% vs. 36.1%, p = 0.012) and heart failure (50.0% vs. 31.9%, p = 0.037). The number of peritonitis episodes within the first six months was not significantly associated with 1-year mortality (p = 0.108). In the multivariable logistic regression model, peritonitis within the first six months was identified as an independent predictor of mortality, increasing the risk of death (OR: 11.438; 95% CI: 1.352–96.749; p = 0.025). Coronary heart disease, heart failure, and peak CRP during the peritonitis attack did not reach statistical significance in this model (all p > 0.05), though this model should be interpreted cautiously given the limited number of events (17) relative to the number of predictors (4). Conclusions: Peritonitis developing during the early phase of therapy is independently associated with an increased risk of one-year mortality in elderly PD patients. Mortality in this population appears to be influenced by early infectious complications alongside underlying cardiovascular comorbidity burden. These findings highlight the clinical importance of close surveillance, early infection prophylaxis, and vigilant therapeutic strategies during the initial months of peritoneal dialysis.