Statistical analysis
POCD
Statistical analysis of the data was performed with SPSS v23.0 and XLSTAT 2018 software. Normality of the data was verified using the Shapiro–Wilk test.Since previous studies POCD studies focus on the major rather than low‐risk surgery, it was difficult to set the appropriate expected cognitive testing target differences in the sample size calculations. We assumed for the 10% intergroup difference in postoperative score decline (15% and 25% of the two groups) and a dropout ratio of 10%, so to achieve the 5% significance level and 80% power, 55 patients should be included in each of the study groups.Depending on the normality of data, the Comparison of baseline and postoperative cognitive score was performed using the Paired Sample 