2.5. Statistical Analysis 
According to the GRANMO Sample Size Calculator (version 7.12, April 2012, Barcelona, Spain), accepting an alpha risk of 0.15 and a beta risk of 0.3 in a two-sided contrast, 48 subjects were required in the first group and 48 subjects in the second group to detect statistically significant differences between two proportions, which for group 1 (intervention group) was expected to be a proportion of 0.5 and for group 2 (control group) 0.7 (estimation of 20% of differences). A loss to follow-up rate of 5% was estimated. The arcsine approximation was used.Quantitative variables are expressed as mean and standard deviation (SD) and student’s 