Supplementary file 1_Development of an interpretable machine learning model for predicting in-hospital mortality in ICU patients with sepsis: a retrospective cohort study.docx

Model performance was assessed by ROC curves (AUC), accuracy, F1 score, sensitivity, specificity, Brier score, expected calibration error, and decision curve analysis. The best-performing model was interpreted using SHAP values.</p>Results<p>Among 431 patients, 198 (45.9%) died during hospitalization. Feature selection using the Boruta algorithm identified 12 key predictors.

The RF model achieved the most balanced overall performance, with an area under the ROC curve of 0.804 (95% CI, 0.730–0.879) in the validation set, accuracy of 0.785, F1 score of 0.778, sensitivity of 0.817, and specificity of 0.757. SHAP analysis identified lactate dehydrogenase and urea as the most influential predictors, followed by age, APACHE II score, and procalcitonin. An interactive web application was developed as a research prototype to demonstrate the feasibility of model deployment.</p>Conclusions<p>We developed and internally validated an interpretable RF-based machine learning model for predicting in-hospital mortality in patients with sepsis.

The model showed acceptable discrimination, reasonable calibration, and potential clinical net benefit in internal validation. SHAP-based interpretation provided insight into key predictive factors, while the web-based calculator demonstrated the feasibility of model deployment. However, external and prospective validation is required before its clinical utility and generalizability can be established.</p>