What is the value of community oximetry monitoring in people with SARS-CoV-2? – A prospective, open-label clinical study

Background

In people with COVID-19, hypoxia at the time of admission is known to be related to mortality. Monitoring of oxygen saturations (SpO₂) is therefore an increasingly common part of community-based care, with the aim of improving the identification of adults who are deteriorating. We set out to investigate whether rigid SpO₂ triggers, or absolute change in SpO₂, is more indicative of deterioration in COVID-19.

Methods

A prospective, uncontrolled, open-label study in a large UK general practice was conducted between May and November 2020. Participants recorded twice daily oximetry and symptom diary for 14 days after test-confirmed COVID-19. Primary outcomes were the proportion of people whose SpO₂ dropped to ≤ 94% and ≤ 92%, the average maximum reduction in SpO₂, and admission to hospital. We also investigated the relationship between MRC Dyspnoea scale, modified Roth score, and SpO₂ through correlation analyses.

Results

52 participants were recruited, following which 41 participants completed the study. The average age was 45.9 years with 63.4% identifying as female. The mean maximum reduction in SpO₂ was 2.8%. The average time to maximum reduction in SpO₂ was 6.4 days. Nine participants (22.0%) had a reduction in SpO₂ to ≤94%. Three of these had a reduction in SpO₂ to ≤92%, for which all three were admitted to hospital. Modified Roth score and SpO₂ were weakly positively correlated (.31). MRC dyspnoea scale score and SpO₂ were moderately negatively correlated (-.53).

Conclusions

A reduction in SpO₂ to ≤92% was found to be highly predictive for admission to hospital. Modified Roth score or MRC dyspnoea scale scores should not be used as proxy measures for oximetry. This study contributes to the ongoing narrative around community-based oximetry and provides insight and recommendations for those currently engaging in or planning to roll out similar schemes.

Strengths and limitations of this study

• This study is pragmatically designed to answer an important clinical question in primary care.

• This study focused on previously published values of SpO₂ for triggering escalation of care and therefore provides answers based on current clinical practice.

• 11 of the 52 patients who were recruited into the study did not return their oximeter or oximetry diary at the end of the study period.

• We did not validate the accuracy or reliability of the oximetry / symptom diaries, as these were self-completed by the participants themselves.

• Other than admission to hospital and mortality within the study period, no other clinical outcomes have been recorded.

Funding statement

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Competing interests

Jane Wilcock has no competing interests to declare.

Ciaran Grafton-Clarke has no competing interests to declare.

Tessa Coulson has no competing interests to declare.