Statistical methods SPSS software version 17.0 (Chicago, IL) was used to perform statistical analysis. The descriptive statistics (mean, standard deviation, confidence interval 95%) was used to characterize the patients in groups. Continuous variables of the 2 groups at baseline were compared using the Student t test (for normally distributed variables) and the Mann-Whitney test (for variables with distribution not considered normal). Categorical variables were evaluated using the chi-square test.