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.