Statistical Analysis
Statistical analysis was performed with Matlab® R2007b (MathWorks Inc., Natick, USA). Qualitative variables were reported with number, percentage and quantitative variables with mean and standard deviation.
We calculated sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and their respective 95 % confidence interval for the diagnosis of a COVID-19 infection with chest CT versus RT-PCR (reference).
The associations between the mortality or morbidity (invasive endotracheal ventilation or ICUH) and chest CT signs of COVID-19 infection (ground glass opacities, crazy paving, consolidation area, subpleural curvilinear bands, bronchial distortion, vascular dilatation, air bubble sign, interlobular thickening, total volume [50-100 % versus < 50%], compatible aspect of organized pneumonia, compatible CT aspect of ARDS, distribution [subpleural, central, and dual i.e. central and subpleural], inferior localization, number of involved lobes (0 to 3 VS 4 or 5 involved lobes) were evaluated using Chi2 tests when applicable (all theorical numbers superior to 5), and Fisher’s exact test otherwise.
All test results with a p-value < 0.05 were considered statistically significant.