Prediction of Mechanical Ventilation in Severe Acute Respiratory Syndrome (SARI) Patients with or without COVID-19 Pneumonia

BACKGROUND: Nearly one third patients with COVID-19 pneumonia who require non-invasive respiratory support ultimately require intubation and mechanical ventilation. ROX index (SaO(2)/FiO(2) to respiratory rate) is a simple and non-invasive predictor of mechanical ventilation in acute hypoxemic respiratory failure. We evaluated role of ROX index and SaO(2)/FiO(2) ratio to predict requirement of mechanical ventilation in Severe Acute Respiratory Infection (SARI) patients with or without COVID-19 infection. METHODS: Data of n=450 adult patients (18- 75y), fulfilling WHO case definition of SARI with clinical suspicion of COVID-19 infection were included in the study. Predictive ability of ROX index and SaO(2)/FiO(2) ratio for mechanical ventilation and hospital mortality were evaluated in this study. RESULTS: Mean (SD) age of the included patients were 46.4 (17.2)y and 166 patients were female. Laboratory confirmed COVID-19 infection on the basis of polymerase chain reaction was documented in 291 (64.6%) patients. ROX index at the time of ICU admission was an excellent predictor of mechanical ventilation [AUROC (95% CI) 0.92 (0.89- 0.94); best cut-off 8.8, sensitivity 73.8% and specificity 91.8%] and mortality [AUROC (95% CI) 0.8 (0.76- 0.84); best cut-off 9.9, sensitivity 67.2% and specificity 80%]. Optimum cut-off values of ROX index for prediction of mechanical ventilation were different in COVID-19 [best cut- off 8.8; sensitivity 74.8% & specificity 90.7%] and non- COVID patients [best cut- off 6.7, sensitivity 97.5% & specificity 77.8%]. SaO(2)/FiO(2) was also able predict requirement of mechanical ventilation [AUROC (95% CI) 0.92 (0.89- 0.94)] and hospital mortality [AUROC (95% CI) 0.81 (0.77- 0.85)] in this cohort. CONCLUSION: ROX index and SaO(2)/FiO(2) ratio were excellent predictor of mechanical ventilation and hospital mortality in severe acute respiratory infection patients irrespective of SARS- CoV(2) positivity status.