Statistical analyses
POCD
The power analysis for this study was based on a pilot study, which showed a POCD (seven days postoperatively) rate of 5% in the QLB group and 35% in the control group. The pilot study was a randomized controlled study with 20 patients in each group. A sample size calculation using IBM SPSS Sample Power version 3.0 (IBM Corp., Armonk, New York, USA) showed that a sample of 24 participants was required in each group to achieve a statistical power of 0.8 with a significance level alpha of 0.05. Considering the 20% drop-out rate, we increased the number of participants to 30 in each group.SPSS V.24.0 (IBM Corp., Armonk, New York, USA) was used to conduct statistical analyses. Normality was assessed using the Kolmogorov-Smirnov test. Normally distributed data were expressed as the mean and SD, non-normally distributed data were expressed as median and quartiles, and categorical data were expressed as frequency and percentages. Intragroup comparisons were analyzed using the Student’s t-test, while differences in non-normally distributed data were assessed using the Mann–Whitney U test. Categorical data were analyzed using the chi-square (