Statistical Analysis
We calculated descriptive statistics to summarize our results. We explored the normal distribution of the continuous variables with the Shapiro-Wilk test. The results were express with mean and standard deviation (SD) if we fail to reject a normal distribution. The results were express with median and interquartile range (IQR) if normal distribution was rejected. We calculated proportions and frequencies for categorical variables. All the analyses were performed using the software SPSS (IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp). A Venn diagram was created with Eulerr web platform/site to display the combination of the grading systems (http://eulerr.co/).(16)