Association of CBC-derived systemic inflammation markers with first-episode peritonitis in peritoneal dialysis

Background Peritoneal dialysis-associated peritonitis (PDAP) remains a major cause of technique failure in peritoneal dialysis (PD) patients. Novel complete blood count-derived inflammatory markers, including the systemic immune-inflammation index (SII), systemic inflammatory response index (SIRI), and aggregate index of systemic inflammation (AISI), may provide accessible tools for early PDAP risk prediction.Methods In this retrospective cohort study, 302 PD patients were stratified according to incident PDAP during follow-up. Restricted cubic splines assessed nonlinear associations. Multivariable logistic regression evaluated independent associations with first-episode PDAP. Receiver operating characteristic curves assessed predictive performance.Results Baseline SII, SIRI, and AISI levels were significantly higher in the PDAP group than in the non-PDAP group (all p < 0.05). Higher Ln-SII (OR: 3.598; 95% CI: 2.204–5.872), Ln-SIRI (OR: 2.425; 95% CI: 1.584–3.714), and Ln-AISI (OR: 2.007; 95% CI: 1.403–2.871) were independently associated with increased PDAP risk (all p < 0.001). SII showed the highest discriminatory performance among the three markers, with an area under the curve of 0.689. A combined model incorporating SII, SIRI, and AISI achieved an AUC of 0.715.Conclusion Higher SII, SIRI, and AISI levels were associated with an increased risk of first-episode PDAP. A combined model demonstrates promising predictive accuracy.