Statistical analysis
SPSS software version 21.0 (SPSS Inc, Chicago, IL, USA) was used for
statistical analysis. The conformity of the data to normal distribution
was examined with the Kolmogorov-Smirnov and Shapiro-Wilk’s tests. The
logarithmic conversion was performed for non-normally distributed
variables. Normally distributed variables were presented as mean and
standard deviation; otherwise, the median and interquartile range were
presented. The comparison of data between the two groups was done by
either student t-test (normal distribution) or Mann-Whitney U (not
normal distribution) test. The chi-square test was performed to compare
categorical data. Correlations were assessed using either Pearson
correlation test for normally distributed data or Spearman’s P when data
were not normally distributed. One-way ANOVA was used to compare
normally distributed variables between the groups, and the Kruskal
Wallis test was used to compare non-normally distributed variables. Post
hoc testing was performed using Tukey’s test. Values of p<0.05
were deemed statistically significant.