Statistical analysis
Normally distributed measurement data are presented as the “mean ± standard”; data that is not normally distributed are presented as “median (range).” The Shapiro- Wilk (SW) test was used to determine whether the continuous variables were normally distributed. Statistical comparisons between the two groups were performed using the Mann-Whitney U test. Categorical variables were described as frequencies or percentages, and comparisons between groups were performed using Pearson’s chi-squared test or Fisher’s exact test. All statistical analyses were performed using IBM SPSS Statistics for Windows (version 19.0; IBM, Corp., Armonk, NY, USA. Statistical significance was set at 