Statistical analysis
All data were analyzed using the IBM Statistical Package for the Social Sciences (SPSS) version 21.0 and MS-Excel 2010 software. The normality distribution of scale variables was checked using the Kolmogorov-Smirnov test. Data were expressed as median (interquartile range) or mean ± standard deviation for those with non-parametric or parametric distribution, respectively. The paired sample t-test or Wilcoxon test was used for dependent samples, whichever is appropriate. Independent samples were compared with the Mann-Whitney U test. Pearson’s chi-square test was used for categorical variables. Scale data were compared with Pearson’s or Spearman’s correlation tests according to their distributions. Two-sided p-values less than 0.05 were considered statistically significant.