Abstract
BACKGROUND: Postoperative delirium (POD) is a common complication in elderly surgical patients associated with adverse outcomes. However, the relationship between low preoperative Barthel Index (BI) and POD remains unclear. PURPOSE: This study investigated the correlation between preoperative BI and POD incidence in elderly patients undergoing non-cardiac surgery. PATIENTS AND METHODS: This prospective cohort study enrolled 298 patients (≥65 years) undergoing elective non-cardiac surgery under general anesthesia. Preoperative BI assessed activities of daily living (ADL) within 24 hours before surgery. POD was screened twice daily until postoperative day 7 or discharge using the 3-Minute Diagnostic Interview for Confusion Assessment Method-defined Delirium (3D-CAM). Univariate and multivariate logistic regression analyzed associations between BI and POD. Restricted cubic spline (RCS) and two-piecewise linear regression explored non-linearity and identified inflection points. Findings were validated using inverse probability of treatment weighting (IPTW), and BI's incremental predictive value was evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: POD incidence was 25.8% (77/298). Multivariate analysis showed lower preoperative BI (OR=0.956, 95% CI: 0.940-0.973, p<0.001), lower BMI (OR=0.860, 95% CI: 0.757-0.977, p=0.020), and advanced age (OR=1.174, 95% CI: 1.102-1.250, p<0.001) independently associated with POD. RCS revealed a nonlinear relationship with inflection at BI=75. Patients with BI<75 had significantly higher POD risk than those with BI≥75 (OR=4.615, 95% CI: 2.377-8.963, p<0.001), robust after IPTW adjustment (42.9% vs 14.5%; adjusted OR=4.445, 95% CI: 2.564-7.707, p<0.001). This association was pronounced in patients with fewer comorbidities, shorter anesthesia duration, and shorter preoperative stays. Incorporating the BI score significantly improved the discrimination of the predictive model for POD. CONCLUSION: Preoperative ADL impairment (BI<75) independently predicts POD in elderly non-cardiac surgery patients. Preoperative BI assessment is recommended for perioperative risk stratification, identifying low-BI patients as targets for preventive interventions.