Acute Pancreatitis: Extrapancreatic Necrosis Volume as Early Predictor of Severity.

ABSTRACT

PURPOSE: To determine the volume of extrapancreatic necrosis that predicts severe acute pancreatitis and to assess the reliability of this threshold in predicting severe acute pancreatitis compared with current scoring systems and C-reactive protein (CRP) levels. MATERIALS AND METHODS: This institutional review board-approved, HIPAA-compliant retrospective study included patients with acute pancreatitis who were examined with computed tomography (CT) 2-6 days after disease onset. Extrapancreatic necrosis volume, Balthazar score, and CT severity index (CTSI) were calculated. CRP levels 48 hours after the onset of symptoms were reviewed. Outcome parameters included organ failure, infection, need for surgery or percutaneous intervention, duration of hospitalization, and/or death. Receiver operating characteristic (ROC) curves were constructed to determine the optimal threshold for predicting clinical outcomes. Pairwise comparisons of areas under ROC curves (AUCs) from the different grading systems were performed. Interobserver and intraobserver agreement in the grading of extrapancreatic necrosis was assessed by using κ statistics. RESULTS: In 264 patients, significant relationships were found between extrapancreatic necrosis volume and organ failure, infection, duration of hospitalization, need for intervention, and death (P < .001 for all). The optimal threshold for predicting severe acute pancreatitis was 100 mL. Sensitivity and specificity were 95% (19 of 20) and 83% (142 of 172), respectively, for predicting organ failure (vs 100% [20 of 20] and 46% [79 of 172] for the Balthazar score and 25% [five of 20] and 95% [163 of 172] for the CTSI). The extrapancreatic necrosis AUC was the highest for all systems. Interobserver and intraobserver agreement based on the 100-mL threshold was considered to be excellent. CONCLUSION: A simple grading system based on an objective criterion such as a threshold of 100 mL of extrapancreatic necrosis provides more reliable information for predicting acute pancreatitis outcomes than do the current scoring systems.