Statistical analysis
Descriptive statistics for categorical variables are reported as absolute value and percentage, and continuous variables are shown as mean and standard deviation. Categorical data were compared using the chi-square test. Continuous variables were compared using the Wilcoxon signed rank test.
We analyzed independent determinants of the additional procedure by performing univariate logistic regression analysis and subsequent multivariate logistic regression analysis, with the p values for entry into and removal from the model set at 0.05 and 0.10, respectively. All analyses were conducted with JMP version 13.0 (SAS Institute Inc., Cary, NC, USA), and a p value of <0.05 was considered statistically significant.