Development and internal validation of a perioperative nomogram for predicting post-operative delirium in geriatric patients with intertrochanteric fractures undergoing internal fixation with pre-operative low-dose dexamethasone.

Objective: To develop and internally validate a nomogram specifically for predicting post-operative delirium (POD) in elderly patients undergoing internal fixation for intertrochanteric fractures, all of whom received a standardized pre-operative low-dose intravenous dexamethasone. Methods: We conducted a retrospective cohort study of 248 patients aged ≥60 years who underwent internal fixation for intertrochanteric fracture at the Third Affiliated Hospital of Zunyi Medical University between January 2023 and October 2025. All patients received 10 mg dexamethasone intravenously 30 min before surgery as part of the institutional protocol for post-operative nausea and vomiting (PONV) prophylaxis. Feature selection was performed using the Boruta algorithm, followed by multivariable logistic regression to identify independent predictors. Model performance was evaluated using area under the curve (AUC), calibration curves, and decision curve analysis (DCA) with 1,000 bootstrap resamples for internal validation. Model interpretability was enhanced using SHAP analysis. Results: The incidence of POD was 12.5% (31/248). Three independent predictors were identified: age (OR = 1.102, 95% CI: 1.029-1.187, Conclusion: We developed the first perioperative nomogram incorporating three perioperative variables to predict POD in geriatric intertrochanteric fracture patients undergoing a standardized pre-operative dexamethasone regimen. This model may facilitate early identification of high-risk individuals within this particular patient subset and support targeted preventive strategies immediately following surgery.