
Statistical analysis (primary and secondary outcomes, subgroup analyses)

Statistical analysis was performed using the Statistical Package for the Social Sciences software (SPSS v. 22.0, SPSS Inc., IL, USA). Shapiro-Wilk w-test revealed that data were not normally distributed. Comparisons were conducted using Mann-Whitney U test or chi-square test; depending on the examined variable (numerical or categorical). Statistical significance was predetermined at the 