Statistical analysis
Sample size was specified by using a power analysis. To detect a significant difference at an effect size of 0.69 and power level of 80% with a 95% confidence level, at least 30 patients were required for each group.Statistical analysis was performed using the SPSS statistical software package, version 20.0 (IBM, Chicago, IL, USA). The normalities of the distributions were tested using the Kolmogorov–Smirnov test. The Wilcoxon signed rank test was used for intragroup comparisons. For intergroup comparisons, the Kruskal–Wallis or chi-square test was used, and for post hoc tests, the Bonferroni correction was used.