Association of blood urea nitrogen to albumin ratio with mortality in acute pancreatitis

Blood urea nitrogen (BUN) and serum albumin (ALB) are strongly associated with the prognosis in acute pancreatitis (AP). The BUN/ALB ratio (BAR) reflects renal, nutritional, inflammatory, and endothelial functions. In this study, we investigated the association between the BAR and all-cause mortality in critically ill patients with AP. Using data from the Medical Information Market for Intensive Care (MIMIC-IV) database, we conducted a retrospective cohort analysis. The relationship between BAR and mortality was assessed through Kaplan–Meier survival curves, restricted cubic spline models, and multivariable Cox proportional hazards regression. The predictive capacity of BAR for 30-day and 1-year mortality was evaluated using receiver operating characteristic analysis. Our study included 780 participants, with 30-day and 1-year mortality rates of 12.6% and 23.6%, respectively. Higher BAR values were associated with poorer survival outcomes. BAR demonstrated superior predictive performance achieving an area under the curve of 0.74, surpassing BUN, ALB, and SOFA scores. The Cox model indicated a significant independent association between elevated BAR and increased mortality risk, with hazard ratios of 1.43 (95% CI 1.20–1.70) for 30-day mortality and 1.37 (95% CI 1.17–1.60) for 1-year mortality. Stratified and sensitivity analyses confirmed the robustness of these findings. Our results suggest that elevated BAR is associated with poor prognosis in critically ill patients with AP and may serve as a valuable tool for early risk stratification and for assessing both short- and long-term prognosis. © The Author(s) 2025.