Statistical methods
Statistical analysis was performed using Statistical Package for Social
Sciences, version 26.0 (SPSS IBM, Chicago, Illinois). All data were
presented as continuous or categorical variables. Categorical data were
expressed as total numbers and percentages. Continuous data were
evaluated for normality using a one-sample Kolmogorov-Smirnov test and
were expressed as the mean ± standard deviation (SD) in normally
distributed or median (interquartile range) in cases of non-normally
distributed continuous variables. Univariate analysis was performed
using either Student t or Mann-Whitney U test for normally and
non-normally distributed continuous variables, respectively. Pearson’s
χ² or Fisher exact tests were used to comparing categorical data
depending on the minimum expected count in each cross-tab. P values
< 0.05 were considered statistically significant. We performed
a linear regression analysis with ANOVA for further analysis of the
variable’s effect. Subgroup analysis of male gender was performed.