Mansoura simple scoring system for prediction of spontaneous bacterial peritonitis: lesson learnt.

BACKGROUND AND OBJECTIVE: Spontaneous bacterial peritonitis (SBP) is a common bacterial infection with life-threatening sequelae in cirrhotic ascites. The purpose of this retrospective cohort study was to recognize the predictors of SBP to build up a noninvasive system to exclude or establish an episode of SBP.

PATIENTS AND METHODS: Of 1194 consecutive patients with cirrhotic ascites, only 966 patients were enrolled in this study. SBP was diagnosed once polymorphonuclear count was at least 250 cells/mm and/or there was a positive ascitic fluid culture result. Biochemical and clinical parameters were evaluated as predictors of SBP. A scoring system was established in the training group of 682 and validated in a second group of 284 participants.

RESULTS: The incidence of SBP was 12.3 and 12% in the training and validation groups, respectively. Age of at least 55 years, mean platelet volume (MPV) of at least 8.5 fl, neutrophil-to-lymphocyte ratio (NLR) of at least 2.5, and C-reactive protein (CRP) of at least 40 mg/l were identified as independent predictors of SBP. A scoring system including these four variables (age, MPV, and NLR with 1 point each, whereas CRP with 2 points) achieves a specificity of 98.2% with a positive predictive value for the diagnosis of SBP of 88.1% (score≥4). At a threshold of 1 point, the negative predictive value is 97.5% with a sensitivity of 92.9%. SBP is not associated with a high Model for End-stage Liver Disease score (P=0.135).

CONCLUSION: The combination of age, MPV, NLR, and CRP in a simple scoring system, Mansoura simple scoring system, supports quick and accurate exclusion or diagnosis of SBP.