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

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.

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.

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).

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.