Abstract: Objective   To explore the relationship between systemic immunoinflammation index (SII) and treatment failure of peritoneal dialysis-associated peritonitis (PDAP).  Methods  The clinical data of PDAP patients treated in the Peritoneal Dialysis Center of the First Affiliated Hospital of Ningbo University from January 2015 to December 2022 were retrospectively analyzed. They were divided into successful treatment group and failed treatment group according to the treatment results. The baseline clinical and laboratory data were compared between the two groups. Logistic regression was used to evaluate the relationship between SII and PDAP treatment failure. Receiver operating characteristic curve (ROC curve) was used to analyze the predictive value of SII for PDAP treatment failure.  Results   This study recruited 87 patients with PDAP, in which 60 (69.0%) were males,  and 63 patients were in the successful treatment group and 24 patients were in the failed treatment group. Compared with the successful treatment group, patients in the failed treatment group had older age (t=-2.643, P=0.010), lower albumin (t=2.189, P=0.031), lower prealbumin ( t=2.189, P=0.031), higher hypersensitive C-reactive protein (Z=-2.821, P=0.005) and higher SII level (Z=-2.934, P=0.003). Multivariate logistic regression demonstrated that higher SII was the independent factor for treatment failure of PDAP (OR=1.001, 95% CI：1.000～1.002, P=0.047). ROC curve results showed that the area under the curve of SII for predicting treatment failure of PDAP was 0.704 (95% CI：0.579～0.829, P=0.003); when the optimal cut-off SII value was set at 2463.23, the sensitivity was 46.0% and the specificity was 92.1%.  Conclusion High SII is independently associated with treatment failure of PDAP. Therefore, SII can be used as a better biomarker to predict treatment failure of PDAP.

Key words: Peritoneal dialysis, Peritonitis, Systemic immune inflammatory index