Oxygen and mortality in COVID-19 pneumonia: a comparative analysis of supplemental oxygen policies and health outcomes across 26 countries

ABSTRACT IntroductionHypoxia is the main cause of morbidity and mortality in COVID-19. During the COVID-19 pandemic some countries have reduced access to supplemental oxygen (e.g. oxygen rationing), whereas other nations have maintained and even improved access to supplemental oxygen. We examined whether such variation in the access to supplemental oxygen had any bearing on mortality in COVID-19. MethodsThree independent investigators searched for, identified and extracted the nationally recommended target oxygen levels for the commencement of oxygen in COVID-19 pneumonia from the 29 worst affected countries. Mortality estimates were calculated from three independent sources. We then applied linear regression analysis to examine for potential association between national targets for the commencement of oxygen and case fatality rates. ResultsOf the 26 nations included, 15 had employed conservative oxygen strategies to manage COVID-19 pneumonia. Of them, Belgium, France, USA, Canada, China, Germany, Mexico, Spain, Sweden and the UK guidelines advised commencing oxygen when oxygen saturations (SpO2) fell to 91% or less. Target SpO2 ranged from 92% to 95% in the other 16 nations. Linear regression analysis demonstrated a strong inverse correlation between the national target for the commencement of oxygen and national case fatality rates (Spearman’s Rho = ?0.622, p < 0.001). ConclusionOur study highlights the disparity in oxygen provision for COVID-19 patients between the nations analysed, and indicates such disparity in access to supplemental oxygen may represent a modifiable factor associated with mortality during the pandemic. Key MessagesWhat is already known?There were no prospective clinical trials we could identify relating to COVID-19 and supplemental oxygen, nor any published studies examining access to supplemental oxygen and mortality in COVID-19.There are a number of studies identifying an association with low oxygen saturations at presentation and mortality in COVID-19 pneumonia.There is good quality evidence that a delay in the correction of hypoxia in pneumonia increases mortality.What are the new findings?This study highlights the different thresholds for commencing supplemental oxygen in patients with COVID-19 across 26 nations.Those countries that provide better access to supplemental oxygen have a statistically significant lower mortality rate.Our results support the consensus view that improving access to supplemental oxygen in COVID-19 pneumonia is likely to reduce mortality.