Prediction of delirium in trauma patients using interpretable machine learning

This study aimed to identify key risk factors for delirium in trauma patients and to develop an interpretable machine learning model using routinely available demographic, clinical, and laboratory data collected at initial trauma center presentation. We analyzed data from 7,806 trauma patients admitted between 2015 and 2023 and constructed an XGBoost-based prediction model evaluated using a hold-out test set. Model interpretability was assessed using Shapley Additive Explanations to quantify feature contributions, threshold effects, and interactions. Delirium occurred in 568 patients (7.3%). The model demonstrated robust predictive performance, with an accuracy of 92.0%, a macro-average AUC of 0.76, and a micro-average AUC of 0.96. SHAP analysis identified age, Injury Severity Score, lactate dehydrogenase, and estimated glomerular filtration rate as the most influential predictors of delirium risk. These variables exhibited clinically meaningful threshold effects, including increased risk above approximately 60 years of age, ISS greater than 15, LDH levels exceeding 350 IU/L, and eGFR below 90 mL/min/1.73 m², as well as notable interactions. Overall, the proposed interpretable machine learning model effectively predicted delirium risk in trauma patients using routine admission data and provides a transparent basis for individualized risk assessment and early prevention strategies in acute trauma care.