[Evaluation of severity and prognosis of acute pancreatitis by CT severity index and modified CT severity index]

Objectives: To explore the role of computed tomography (CT) severity index (CTSI) and modified CT severity index (MCTSI) in assessing the severity of acute pancreatitis (AP) under the revised Atlanta classification (RAC) and predicting the clinical prognosis. Methods: Based on the prospectively entered AP database, the clinical data of consecutive adult AP inpatients admitted to the Department of Gastroenterology of the First Affiliated Hospital of Nanchang University from January 2012 to December 2020 were retrospectively screened. The imaging data were independently evaluated by two radiologists and entered to the database to calculate the CTSI and MCTSI scores. Their relationship with the difference of RAC severity grade and clinical prognosis was analyzed. Compared with Acute Physiology and Chronic Health Assessment Ⅱ (APACHE Ⅱ) score, the receiver operating characteristic curve was used to evaluate the predictive value of CTSI and MCTSI scores for persistent organ failure and infectious pancreatic necrosis (IPN). Results: A total of 2 612 patients with AP, aged (50±15) years, were included in the study, including 1 547 males (59.2%) and 1 065 females (40.8%). According to RAC standard, AP was divided into 699 cases (26.8%) of mild pancreatitis (MAP), 1 098 cases (42.0%) of moderately severe pancreatitis (MSAP), and 815 cases (31.2%) of severe pancreatitis (SAP). MCTSI judged AP severity similarly to RAC, with 668 cases of MAP (25.6%), 1 207 cases of MSAP (46.2%) and 737 cases of SAP (28.2%), while CTSI judged SAP patients less(400 cases, 15.3%). The severity of AP determined by CTSI and MCTSI scores was significantly correlated with clinical prognosis (r=0.06-0.43, all P<0.05). Compared with APACHE Ⅱ score, CTSI had the highest area under the curve (AUC) for predicting IPN (AUC=0.85, 95%CI: 0.83-0.87), followed by MCTSI (AUC=0.82, 95%CI: 0.80-0.85). APACHE Ⅱ was more accurate in predicting persistent organ failure than CTSI and MCTSI scores,with AUC of 0.73 (95%CI: 0.71-0.75), 0.72 (95%CI: 0.70-0.74) and 0.72 (95%CI: 0.70-0.74), respectively. Conclusions: AP severity judged by MCTSI is consistent with RAC, and SAP patients judged by CTSI are less than RAC. CTSI and MCTSI are significantly correlated with clinical prognosis. CTSI and MCTSI have higher accuracy in predicting IPN, but lower accuracy in predicting persistent organ failure than APACHE Ⅱ.