Combining bedside index of severity in acute pancreatitis (BISAP) and Charlson comorbidity index improves early risk stratification in biliary acute pancreatitis

Risk stratification in acute pancreatitis (AP) remains a clinical challenge. Because AP populations are diverse, focusing on one etiology might reveal interesting insights concerning predictors of outcomes. In this retrospective multicenter cohort study, all patients with biliary AP admitted between 2018 and 2021 were included. Predictors of clinical outcomes - including severity, ICU-admission, complications, and 90-day mortality - were assessed. In total, 217 biliary AP patients, mean age 65.9 years (SD 17.4), 49.3% female, were included, with a median length of stay 7 days (IQR 4;11). BISAP scores were 0 in 30.0%, 1-2 in 63.5%, and 3-5 in 6.4% of patients. Higher BISAP and Charlson comorbidity index (CCI) were significantly associated with worse outcomes, including ICU admission, persistent organ dysfunction, and mortality (p < 0.001). When combined, BISAP and CCI identified five risk groups with progressively increasing rates of complications and mortality. Notably, 41.1% of patients fell into the lowest risk group, with only 2 ICU admissions, and with an uncomplicated course in 97.6% of cases, supporting potential early discharge. Mortality in the very-high risk group (BISAP 3-5, CCI >= 6) was 50%. The combination (BISAP-C) enhances early prognostication in biliary AP and may guide individualized management and healthcare resource utilization.