Fig. 2.

Receiver operating characteristic curves for models classifying patients with COVID-19 vs. non-COVID-19 ARDS. a. Complete model. The use of three machine learning algorithms (elastic net, support vector machine (SVM), and random forest (RF)) yielded an accuracy of up to 93%, with a 10-fold cross validation repeated four times and based on the selection of 19 features (elastic net), 16 features (random forest) or all 65 features (support vector machine) from the full dataset. After internal cross-validation, the sensitivity was 90% and the specificity was 94%. b. Model with the four most important features only. After internal cross-validation, the sensitivity ranged from 90% to 98% and the specificity ranged from 88% to 94%.