2.4 Statistical data analysis
Normality of data distributions were examined with the Kolmogorov-Smirnov test. Continuous variables are expressed as mean ± SD or median with interquartile range as appropriate, and categorical variables are expressed as a percentage. For the continuous variables, comparisons between two groups were made using t-tests while for 3 or more groups with ANOVA and Bonferroni test for multiple comparisons. All the analyses were conducted in SPSS version23 [SPSS Inc., Chicago, IL, USA], Microsoft Windows version, and P ≤ 0.05 from 2-sided tests was considered statistically significant.