Abstract: Objective To investigate the survival outcomes and risk factors for mortality in cirrhotic patients with probable spontaneous bacterial peritonitis (SBP). Methods We retrospectively analyzed the clinical data of 323 cirrhotic patients with ascites admitted from June 2021 to May 2022, including 115 patients with SBP [ascites polymorphonuclear leucocyte (PMN) count ≥250/mm3], 52 patients with bacterascites (PMN count <250/mm3 with positive microbiological finding in ascites), 67 patients with probable SBP (PMN count <250/mm3 with negative microbiological finding in ascites but clinical symptoms of SBP) and 89 patients without infection (PMN count <250/mm3 with negative microbiological finding without clinical symptoms of SBP). The clinical characteristics, laboratory data and 90-day mortality of the patients were compared among the 4 groups. Cox proportional hazard model and propensity score matching (PSM) in a 1∶1 ratio were used to analyze the risk factors for mortality in patients with probable SBP. Results The patients with probable SBP had a 90-day mortality rate of 43.28%, similar to those of patients with SBP (46.95%, P=0.121) and bacterascites (48.07%, P=0.805) but significantly higher than that of non-infected patients (11.23%, P<0.001). In the 46 pairs of patients matched using PSM, the 90-day mortality rates were higher in probable SBP group than in non-infected group both before (43.28% vs 11.23%, P<0.001) and after PSM (34.78% vs 15.21% , P=0.038). Cox regression analysis indicated that probable SBP was an independent predictor of 90-day mortality in cirrhotic patients with ascites (HR=1.539, 95% CI: 1.048-2.261, P=0.028). A Model for End-Stage Liver Disease (MELD) score >15 (HR=1.943, 95% CI: 1.118-3.377, P=0.018) and procalcitonin level >0.48 ng/mL (HR=1.989, 95% CI: 1.111-3.560, P=0.021) at diagnostic paracentesis were both independent risk factors for 90-day mortality in patients with probable SBP. Conclusion Cirrhotic patients with probable SBP have poor survival outcomes, and their management should be further optimized based on their MELD score and procalcitonin level.

Key words: liver cirrhosis; spontaneous bacterial peritonitis; prognosis; risk factors; propensity score matching