Predicting mortality in intensive care unit patients with acute pancreatitis using an interpretable machine learning model.

Background: Acute pancreatitis (AP) in the intensive care unit (ICU) is linked to elevated in-hospital mortality rates. Timely identification of high-risk patients remains challenging. This study aimed to develop an interpretable machine learning model for predicting in-hospital mortality in ICU patients with AP and to identify key contributing factors. Methods: A retrospective analysis was performed on 306 ICU patients diagnosed with AP. After data preprocessing and feature selection via the Least Absolute Shrinkage and Selection Operator (LASSO), seven machine learning models were developed: decision tree, random forest, XGBoost, support vector machine (SVM), multilayer perceptron, k-nearest neighbors (KNN), and logistic regression. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), Brier score, calibration plots, and decision curve analysis (DCA). The SHapley Additive exPlanations (SHAP) framework was utilized to interpret model predictions and assess feature importance rankings. Results: Multivariate logistic regression analysis identified the following independent risk factors for in-hospital mortality in ICU patients with AP: acute physiology and chronic health evaluation (APACHE II) score, activated partial thromboplastin time (APTT), albumin (Alb), blood urea nitrogen (BUN), creatinine (Cr), use of vasoactive agents, and ICU length of stay. The AUC values for the seven machine learning models in the training set were DT (0.947), RF (0.900), XGBoost (0.887), SVM (0.901), MLP (0.837), KNN (0.983), and LR (0.876). In the validation set, the corresponding AUC values were DT (0.698), RF (0.850), XGBoost (0.878), SVM (0.892), MLP (0.822), KNN (0.755), and LR (0.858). Although DT and KNN demonstrated high sensitivity and specificity in the training set, their performance was suboptimal in the validation set. SHAP analysis ranked APACHE II score as the most influential predictor of mortality. Conclusion: An interpretable SVM model incorporating routinely available clinical variables effectively predicts in-hospital mortality in ICU patients with AP. SHAP-enhanced interpretation highlights key predictors and enhances model transparency, supporting clinical decision-making.