2.4 | Statistical Methods
The analyses were performed using the SPSS statistical package (version 22.0; SPSS Inc., Chicago, USA). The measurement data in accordance with the normal distribution were expressed by mean ± SD. The independent sample t -test was used for the inter-group comparison and the paired sample t -test for the intra-group comparison. The non-normal distribution data were expressed by median and quartile interval (MEDIAN, IQR), and the counting data were described by frequency, percentage, and some cases. The independent sample Mann—Whitney U-test was used for the inter-group comparison, and paired sample Wilcoxon test was used for the intra-group comparison. Ap -value < 0.05 was considered statistically significant.