Sample size calculation and statistical analysis
REGRESSION
The sample size was calculated based on pilot study data. The mean APAIS score immediately before surgery was 20.5 and the standard deviation was 6.0 in patients undergoing gynecologic surgery with the ERAS protocol. We assumed that the APAIS score of the CHD with gum group compared to the CHD group would need to decrease by 20% for clinically meaningful significance to be detected. With an alpha of 0.05 and a beta of 0.9, 45 participants are required in each group using the independent two-sample t-test. We enrolled 52 participants in each group to account for an expected 15% attrition rate, with a total of 104. All continuous data were tested for normality by the Shapiro–Wilk test. Normally distributed data were presented as means (standard deviations [SD]) and analyzed using independent two-sample t-test. Skewed data were presented as median (interquartile range [IQR]) and analyzed using Wilcoxon’s rank sum test. For categorical variables, all data were summarized as the number (%) and differences between groups were analyzed using the chi-square test or Fisher’s exact test as appropriate. The association between QoR-15K and APAIS scores measured in the preoperative holding area was analyzed using a linear regression model. A value of p < 0.05 was considered statistically significant. The individual p-value of multiple comparisons was adjusted using Bonferroni post-correction. Statistical analysis was performed using SAS version 9.4 (SAS Institute Inc, Cary, NC, USA).