Statistical analysis

The Student’s t test was used to compare two independent groups as a scalar variable. The Levene test was used to verify the homogeneity of variances of each variable for each group. Due to the heterogeneity of variances, we used the Student’s t test values observing non-equal variances. The association/relationship/dependence between two categorical variables of interest was determined using the chi-square test. In the event of a significant association between two variables of interest, we assessed the statistical odds ratio (OR). Fisher’s exact test was adopted to compare the groups as the proportion of occurrence of a specific event. The chi-square test Mantel-Haenszel was applied to evaluate association/linear relationship between two categorical variables. The OR and 95% confidence interval (CI) of each of the factors were calculated. Statistical significance was established when p < 0.05.