SpO2/FiO2 ratio. A promising index in predicting mortality in COVID-19 patients

Abstract

Objectives: identifying high-risk COVID-19 patients is critical for emergency department decision-making. The primary objective of the study was to identify new independent predictors of mortality and their prognostic utility in combination with traditional pneumonia risk assessment scores. Methods: a retrospective study was performed in two Italian University Hospitals. A multivariable logistic model was used to locate independent parameters associated with mortality. Results: age, PaO2/FiO2 (P/F), and SpO2/FiO2 (S/F) ratios were found to be independent parameters associated with 30-day mortality. Study found that PSI was superior to CRB-65 and NEWS in predicting 30-day mortality (AUC: 0.766 vs. 0.763, p=0.981; AUC: 0.766 vs. 0.616, p=0.003). Combination of S/F with CRB-65 and NEWS improved the prognostic accuracy of score compared to “scoring without S/F” (p<0.001 vs. p<0.001 respectively) and compared to PSI (p=0.005 vs. p=0.483 respectively). Combination of P/F with CRB-65 and NEWS produced similar results. Conclusions: in our study, S/F was an independent parameter of 30-day mortality, and being a non-invasive parameter, it could be a valuable tool for staging COVID-19 patients upon admission to the hospital. The combination of S/F and CRB-65 performed similarly to the PSI, and can be a valid alternative to ferruginous PSI calculation and could provide valuable support for decision-makers.

A Simple Risk Formula for the Prediction of COVID-19 Hospital Mortality

“…Not only has a high positive correlation between the S/F ratio and the P/F ratio been shown [6,27], but the S/F ratio has helped predict various clinical outcomes [28] including ARDS in COVID-19 patients requiring oxygen therapy [29]. Recently, the S/F ratio was found to be an independent risk parameter in predicting 30-day mortality in COVID-19 patients; moreover, combined with CRB-65, it performed similarly to the pneumonia severity index [30].…”