PaO 2 /FiO 2 ratio forecasts COVID-19 patients' outcome regardless of age: a cross-sectional, monocentric study

We studied the predictive value of the PaO /FiO ratio for classifying COVID-19-positive patients who will develop severe clinical outcomes. One hundred fifty patients were recruited and categorized into two distinct populations ("A" and "B"), according to the indications given by the World Health Organization. Patients belonging the population "A" presented with mild disease not requiring oxygen support, whereas population "B" presented with a severe disease needing oxygen support. The AUC curve of PaO /FiO in the discovery cohort was 0.838 (95% CI 0.771-0.908). The optimal cut-off value for distinguishing population "A" from the "B" one, calculated by Youden's index, with sensitivity of 71.79% and specificity 85.25%, LR+4.866, LR-0.339, was