Dynamic Controlling Nutritional Status Score and the Prediction of Early Peritonitis in Peritoneal Dialysis

Background: Peritoneal dialysis-associated peritonitis (PDAP) remains a leading complication of PD. The controlling nutritional status (CONUT) score, a composite index reflecting nutritional and immune status, may serve as a promising predictor to facilitate early risk stratification. Methods: In this multicenter prospective cohort study, 675 patients who initiated PD between December 1, 2012, and June 30, 2022, across three medical centers in China were enrolled and followed until June 30, 2023. Baseline CONUT score, 6-month CONUT score, and changes over time were evaluated for their association with early-onset PDAP, defined as peritonitis occurring within 12 months of PD initiation. Statistical analyses included multivariable logistic regression, receiver operating characteristic (ROC) curve analysis, and Kaplan–Meier (K-M) survival analysis. Results: Over a median follow-up period of 41.8 months, 253 patients (37.5%) developed PDAP, including 82 cases of early-onset PDAP. Multivariable logistic regression identified baseline total cholesterol (OR 1.354, 95% CI 1.098–1.670; p = 0.005), neutrophil-to-lymphocyte ratio (OR 1.073, 95% CI 1.005–1.146; p = 0.035), and 6-month CONUT score (OR 1.239, 95% CI 1.126–1.364; p < 0.001) as independent predictors of early-onset PDAP (vs. no PDAP). In comparisons between early- and late-onset PDAP, older age (OR 1.027, 95% CI 1.006–1.048; p = 0.011), longer PD duration (OR 1.027, 95% CI 1.015–1.040; p < 0.001), and lower 6-month CONUT score (OR 0.806, 95% CI 0.721–0.902; p < 0.001) were independently associated with an increased likelihood of late-onset PDAP. ROC curve analysis yielded an AUC of 0.671 (95% CI 0.603–0.739) for distinguishing early-onset PDAP from no PDAP, and 0.746 (95% CI 0.682–0.810) for early-onset vs. late-onset PDAP. K-M analysis showed significantly lower early-onset PDAP risk in patients with 6-month CONUT score ≤ 4 (p < 0.001) and in those with a CONUT score change < 0 (p = 0.001). Among patients with PDAP, both 6-month CONUT score (p < 0.001) and CONUT score change (p = 0.002) significantly influenced the timing of onset. Conclusion: The 6-month CONUT score is an independent predictor of early-onset PDAP. Dynamic monitoring of nutritional-immune status—particularly changes in CONUT score—may offer valuable prognostic information and support early, individualized preventive strategies in patients undergoing PD. Funding: Government Support – Non-U.S.