Serum albumin and risk of peritonitis in peritoneal dialysis patients: experience of a renal program.

Abstract

Introduction: Peritonitis associated with peritoneal dialysis remains a major infectious complication. It is linked to hospitalization, technique failure, catheter removal, transfer to hemodialysis, and increased morbidity. Serum albumin is a widely available biomarker that reflects not only nutritional status but also inflammation, clinical frailty, and immunological vulnerability. Therefore, assessing it could be useful for stratifying the risk of peritonitis in patients undergoing peritoneal dialysis. According to the 2022 International Society for Peritoneal Dialysis (ISPD) guidelines, preventing peritonitis requires a multifactorial approach that includes the continuous assessment of the patient's nutritional and inflammatory status (1). Serum albumin is a widely available, low-cost biomarker reflecting not only nutritional status but also the presence of systemic inflammation, clinical frailty, and immunological vulnerability. Recent studies suggest that hypoalbuminemia (<3.5 g/dL) is associated with impaired peritoneal membrane function and a compromised local immune response, thereby increasing susceptibility to infections (2), (3). The aim of this study was to evaluate the association between serum albumin levels and the risk of developing peritonitis in a cohort of peritoneal dialysis patients, using survival analysis to stratify clinical risk.

Materials and methods: An observational, analytical, retrospective study was conducted on adult patients undergoing peritoneal dialysis (PD) who had remained on the modality for more than three months and had available serum albumin records. Patients with incomplete follow-up or those who switched to hemodialysis before the three-month mark were excluded. Demographic variables (age, sex), clinical variables (diagnosis of end-stage renal disease, comorbidities, duration of PD), and laboratory variables (mean serum albumin, hemoglobin, potassium) were collected. The primary outcome was the occurrence of at least one episode of peritonitis, defined according to ISPD criteria (cloudy effluent, leukocyte count >100/µL with >50% polymorphonuclear cells, and/or positive culture) (1). Patients were classified into two groups based on mean serum albumin levels: <3.5 g/dL (hypoalbuminemia) and ≥3.5 g/dL. Continuous variables were expressed as mean ± standard deviation, and categorical variables as frequencies. Fisher's exact test was used to compare proportions. Peritonitis-free survival was estimated using the Kaplan-Meier method, and curves were compared using the log-rank test. A Cox proportional hazards model was fitted to calculate the hazard ratio (HR) for peritonitis associated with hypoalbuminemia, adjusting for age and duration of PD. A p-value < 0.05 was considered statistically significant. The analysis was performed using Python.

Results: Thirty-one adult patients enrolled in the peritoneal dialysis program were included and followed for 12 months. The mean age was 47.4 ± 17.3 years, and the mean duration of peritoneal dialysis was 9.8 ± 9.1 months. When patients were stratified by their average serum albumin level, 5 patients (16.1%) presented with hypoalbuminemia (<3.5 g/dL), while 26 patients (83.9%) maintained levels ≥3.5 g/dL. Regarding the incidence of peritonitis, it was observed that 18 of the 31 patients (58.1%) experienced at least one episode during the follow-up period. Furthermore, a marked difference in incidence was observed: 100% (5/5) of patients with hypoalbuminemia developed peritonitis, compared to 50% (13/26) of patients with albumin levels ≥3.5 g/dL. This finding corresponds to a relative risk (RR) of 2.00 (95% CI: 1.36–2.94; p=0.058, Fisher's exact test).

Kaplan-Meier survival analysis demonstrated that the median peritonitis-free time was significantly shorter in the hypoalbuminemia group (6 months) than in the reference group (11 months; log-rank test: p=0.0096). Finally, the Cox proportional hazards model (Table 2) confirmed that hypoalbuminemia is a robust, independent predictor of peritonitis. After adjusting for age and time on dialysis, patients with albumin levels <3.5 g/dL showed a Hazard Ratio (HR) of 9.68 (95% CI: 2.70–34.65; p<0.001), indicating a nearly 10-fold higher risk of developing a first infectious episode, regardless of other clinical variables.

The finding that the Cox model yields an HR of 9.68 (p=0.011) is remarkable; in a cohort of 31 patients, this value indicates that those with hypoalbuminemia are at nearly 10 times the risk of developing a first episode of peritonitis compared to those with normal albumin levels, irrespective of age or duration of dialysis.

Conclusions: Serum albumin <3.5 g/dL is an independent, high-risk predictor for the development of peritonitis in patients undergoing peritoneal dialysis (PD), whereas other variables—such as age and duration of PD treatment—are significant predictors (p > 0.05), confirming that hypoalbuminemia is the true independent driver of infection risk. Routine monitoring of this parameter enables the early identification of the most vulnerable patients and facilitates the implementation of targeted, personalized preventive interventions in strict compliance with ISPD quality standards. Prospective studies with larger cohorts are recommended to validate these findings and establish early nutritional and immunological intervention protocols.