Statistical analysis
Continuous variables are presented as mean and standard deviation in cases of normal distribution, as well as median and interquartile range (IQR) values in cases of non-normal distribution. Categorical variables are presented as frequencies and percentages. To evaluate the difference between the two groups in continuous variables, the normality test was performed followed by the independent T-test or Wilcoxon's rank sum test. For categorical data, a chi-square test or Fisher's exact test was performed. All statistical analyses were performed using SPSS version 21.0 for Windows (IBM Corp, Armonk, NY, USA), and the significance level was set to 0.05.