2.4. Statistical analysis
Quantitative variables were described as median with interquartil range (IQR). Relative frequencies were used for categorical variables.  Data were stratified for patients who were positive and negative and their distributions compared with student t test or Mann Whitney test (non-normal distribution). Categorical variables were analysed by Chi-square test. Statistical data were analysed using Prism software v8.0 (GraphPad Software, San Diego, CA, USA). Values of p< 0.05 were considered significant for all analyses.