The PaO2/FiO2 ratio on admission is independently associated with prolonged hospitalization in COVID-19 patients.

Introduction: The early identification of factors that predict the length of hospital stay (HS) in patients affected by coronavirus desease (COVID-19) might assist therapeutic decisions and patient flow management.
Methodology: We collected, at the time of admission, routine clinical, laboratory, and imaging parameters of hypoxia, lung damage, inflammation, and organ dysfunction in a consecutive series of 50 COVID-19 patients admitted to the Respiratory Disease and Infectious Disease Units of the University Hospital of Sassari (North-Sardinia, Italy) and alive on discharge.
Results: Prolonged HS (PHS, >21 days) patients had significantly lower PaO2/FiO2 ratio and lymphocytes, and significantly higher Chest CT severity score, C-reactive protein (CRP) and lactic dehydrogenase (LDH) when compared to non-PHS patients. In univariate logistic regression, Chest CT severity score (OR = 1.1891, p = 0.007), intensity of care (OR = 2.1350, p = 0.022), PaO2/FiO2 ratio (OR = 0.9802, p = 0.007), CRP (OR = 1.0952, p = 0.042) and platelet to lymphocyte ratio (OR = 1.0039, p = 0.036) were significantly associated with PHS. However, in multivariate logistic regression, only the PaO2/FiO2 ratio remained significantly correlated with PHS (OR = 0.9164; 95% CI 0.8479-0.9904, p = 0.0275). In ROC curve analysis, using a threshold of 248, the PaO2/FiO2 ratio predicted PHS with sensitivity and specificity of 60% and 91%, respectively (AUC = 0.780, 95% CI 0.637-0.886 p = 0.002).
Conclusions: The PaO2/FiO2 ratio on admission is independently associated with PHS in COVID-19 patients. Larger prospective studies are needed to confirm this finding.
Competing Interests: No Conflict of Interest is declared
(Copyright (c) 2021 Angelo Zinellu, Andrea De Vito, Valentina Scano, Panagiotis Paliogiannis, Vito Fiore, Giordano Madeddu, Ivana Maida, Elisabetta Zinellu, Arduino Aleksander Mangoni, Luigi Benedetto Arru, Ciriaco Carru, Sergio Babudieri, Pietro Pirina, Alessandro Giuseppe Fois.)