Statistical analysis
The data were analyzed using the Statsitical Package for the Social Sciences, version 16.0 (SPSS Inc., Chicago, USA). The continuous variables with a normal distribution were presented as means ± standard deviations and analyzed using the independent-samples t-test (2-group comparisons). Otherwise, they were presented as medians (ranges) and analyzed using the Mann-Whitney U test. Continuous data from repeated measurements were statistically analyzed using repeated measurements analysis of variance. Categorical data were presented as numbers and precentages (%); they were analyzed using the Chi-square test. 