 Statistical analysis Qualitative variables will be expressed as frequency and percentage, using the Chi square or Fisher test to compare groups, as appropriate. Quantitative variables will be shown mean and standard deviation SD or median and interquartile range P25-P75, depending on the normality of the distribution, and groups will be compared using Student t or Mann-Whitney U test, respectively. A P-value 0.05 will be considered significant. All analyses will be done using IBM SPSS Statistics IBM Statistics, Markham, ON, Canada. 