Prognostication of Oxygen Requirement in Non-severe SARS-CoV-2 Infection

Background

At the time of writing the novel betacoronavirus SARS-CoV-2 has infected more than 11 million individuals and killed more than 500,000. The most recent epidemiological surveillance curve shows that the number of new infections continues to rise, with over 230,000 new cases reported in the last 24 hours.

Whilst the absolute number of deaths attributable to COVID-19 is substantial, effectively managing high patient volumes is also a major challenge facing health systems, particularly in under-resourced settings. With an estimated case-fatality rate amongst symptomatic patients of between 1-2%, it is vitally important that health workers are able to accurately identify the majority of patients at low risk for progression to severe disease. These patients can be safely discharged away from the health facility ensuring the available resources are allocated to patients most likely to benefit. If low-risk patients cannot be readily identified, there is a real risk that health facilities in these regions will be overrun, with consequent substantial avoidable mortality.

COVID-19 has already started to hit extremely vulnerable populations in refugee camps and conflict areas. In Bangladesh, cases within the Rohingya refugee megacamps have already been reported, and local transmission is ongoing. Such contexts already suffer from a lack of medical facilities and even a moderate number of COVID-19 cases will overburden existing, and proposed, capacity. Having the ability to prognosticate the need for supplemental oxygen (the main treatment available in these settings) through measurement of parameters available at the time of arrival at a healthcare facility would strengthen the capability to identify those patients presenting with moderate symptoms that can be safely discharged away from the facility. Based on recent estimates, only 20% of all symptomatic patients with COVID-19 develop a requirement for supplemental oxygen.

Although existing prognostic scores have yielded disappointing results in patients with SARS-CoV-2 infection a number of demographic, clinical and laboratory parameters are associated with a more severe disease course and worse patient outcomes. However, to our knowledge, few studies have examined the performance of prognostic markers in patients who do not require supplemental oxygen at presentation. Only one of these studies included outpatient or ambulatory care settings and none were conducted in resource-limited settings. Hence, whether measurement of these parameters can inform the decision to safely discharge a patient away from a health facility is as yet unclear.