Statistical analysis:
All statistical analyses were performed using SPSS for Windows (Version 21.0; SPSS Inc., Chicago, IL, USA). Quantitative data were tested for normality of distributions by Kolmogorov–Smirnov test, and then compared by Unpaired Student’s t -test, Mann-Whitney U test for normal and non-normal data, respectively. Qualitative data were analyzed by the Chi-square test, and a P-value of < 0.05 was considered as significant.