Predicting Postoperative Delirium in Cardiac Surgery Patients: Integrating Psychological and Infectious Risk Factors

Background: Postoperative delirium (PD) is a frequent complication following cardiac surgery, associated with increased morbidity and prolonged hospital stay. Accurate preoperative risk prediction remains challenging. This study aimed to develop and validate a clinical model to predict PD in cardiac surgery patients. Methods: We retrospectively enrolled 1119 adult patients undergoing open-chest cardiac surgery between January 2020 and September 2021. Patients were randomly divided into a training cohort (n = 783) and a validation cohort (n = 336). Delirium within 7 days postoperatively was assessed using the Confusion Assessment Method for the ICU (CAM-ICU). Univariable and multivariable logistic regression analyses identified independent predictors. Model performance was evaluated with area under the receiver operating characteristic curve (AUC), calibration plots, and decision curve analysis. Results: Delirium occurred in 90 patients (8.0%). Four variables were independently associated with PD: history of stroke, preoperative anxiety (Self-Rating Anxiety Scale), postoperative infection, and duration of mechanical ventilation. The model showed good discrimination, with AUCs of 0.81 (95% CI: 0.74–0.88) in the training cohort and 0.83 (95% CI: 0.74–0.93) in the validation cohort. Calibration plots demonstrated good agreement between predicted and observed risk. Decision curve analysis supported its clinical utility. Conclusions: We developed and internally validated a four-factor model to predict delirium after cardiac surgery. The inclusion of psychological and infectious factors improves its predictive accuracy. This tool may assist clinicians in identifying high-risk patients and implementing targeted preventive strategies.