Statistical analysis
Statistical analysis was carried out using SPSS 21.0 software. Quantitative data are expressed as mean±SD and were compared with 2-sample t tests for independent samples, whereas dichotomous variables were reported as absolute values and proportions. Differences in proportion were compared with a χ2 test or Fisher exact test as appropriate. Univariate analysis was performed with the Kaplan–Meier test and with the Cox regression analysis. For each variable, the odds ratio (OR), 95% confidence interval (CI), and P value were provided. Variables significantly associated with occurrence of delirium event after univariate analysis (P<0.05) were entered in a multivariable logistic regression model to identify the independent predictors. Additionally, we calculated the area under receiver operating characteristic (ROC) curve to assess the predictive value of SAS score for risk of delirium in patients following OPCABG.