Predictive value of the risk stratification.

A: Patients characteristics that were significantly different between the groups (*, P < 0.01). Error bar demonstrated 95% CI. B: ROC curve analysis to determine optimal cut-off values of age, gait speed in Get-up and Go test, and fall risk assessment scores. The AUC values were 0.89 in age, 0.87 in Get-up and Go test, and 0.79 in fall risk assessment score. The optimal cut-off values were age older than 75 years, slower than 13.0 s in the Get-up and Go test, and higher than 10 points in fall risk assessment score. C: Patients were categorized according to the number of independent predictors (>75 years old, Get-up and Go > 13.0 s, eGFR decline > 30%) for postoperative delirium (scores 0–3). The occurrence of postoperative delirium was 0% in score 0, 1.4% in score 1, 26% in score 2, and 67% in score 3 (P < 0.001). D: Predictive accuracy of selected three factors by the ROC curve showed that the AUC value was 0.952 (P < 0.001, 95% CI 0.902–1.00).