Prediction of spontaneous bacterial peritonitis in cirrhotic ascites by a simple scoring system

BACKGROUND AND AIMS: Spontaneous bacterial peritonitis (SBP) is a life-threatening complication in patients with liver cirrhosis. The aim of this prospective study was to identify predictors of SBP in order to develop a noninvasive method to identify or exclude an episode of SBP.

PATIENTS AND METHODS: Three hundred and ninety-two consecutive patients, who underwent paracentesis from March 2008 through January 2012 in our department due to cirrhotic ascites, were screened. Ninety-six patients were excluded, mostly due to prior application of antibiotics. SBP was defined by an absolute neutrophil count≥250 cells/µL ascites. We evaluated various clinical and laboratory parameters as potential predictors of SBP. A scoring system was developed in a training set of 220 and validated in a second set of 76 patients.

RESULTS: Fifty-eight patients (26%) in the training set and 17 patients in the validation set (22%) suffered from SBP. Thrombocytopenia≤100,000 cells/µL, age>60 years and CRP>60 mg/L were identified as independent predictors of SBP. A scoring system combining these three parameters (weighting thrombocytopenia and age with 1 point each, but CRP with 2 points) reaches a positive predictive value for the diagnosis of SBP of 81.8% with a specificity of 98.8% (score≥3). The negative predictive value at a threshold of 1 point is 93.5% with a sensitivity of 87.9%. Notably, a high MELD score is not associated with SBP (p=0.3344).

CONCLUSIONS: Combination of age, CRP and platelet count in a simple scoring system helps in the rapid diagnosis or exclusion of SBP.