**2.6 Statistical analyses**

No sample size assumptions have been made for this trial. Continuous variable are presented as mean ± standard deviation (SD). Categorical variables are displayed as percentages. To analyze the differences between the treatment groups, the Student *t* test was used for the continuous variables and the chi-square test for the categorical variables For each endpoint, a two-sided 95% confidence interval (CI) was calculated and an overall χ2 test comparing the two treatment groups was used. Also, we performed simple and multivariate, linear and logistic regression analysis and we calculated relative risks and correlation coefficients. For the primary endpoints Kaplan–Meier curves were constructed and log-rank tests were used. All statistical analyses were performed using SYSTAT and SPSS software. A *p* value <0.05 defined the statistical significance.
