The data analysis was performed using SPSS 19.0 (SPSS Inc., Chicago, IL, USA). Categorical data were expressed as number (with percentage, n%) and compared with Chi-square test or Fisher exact test. Continuous data were presented as mean levels (with standard deviation) or median (with interquartile range) and compared via the Mann–Whitney U-test or Student's t-test appropriately. The univariate and multiple logistic regression analyses were plotted to evaluate the predicative validity of pre-, intra-, or postoperative variables for POD. All statistical tests were bilateral probability and P < 0.05 was considered significant.