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

  1. Jane Wilcock
  2. Ciaran Grafton-Clarke
  3. Tessa Coulson

Reviewed by

Read the full article See related articles

Listed in

Log in to save this article

Abstract

Background

In people with COVID-19, hypoxia at the time of admission is known to be related to mortality. Monitoring of oxygen saturations (SpO 2 ) 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 SpO 2 triggers, or absolute change in SpO 2 , 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 SpO 2 dropped to ≤ 94% and ≤ 92%, the average maximum reduction in SpO 2 , and admission to hospital. We also investigated the relationship between MRC Dyspnoea scale, modified Roth score, and SpO 2 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 SpO 2 was 2.8%. The average time to maximum reduction in SpO 2 was 6.4 days. Nine participants (22.0%) had a reduction in SpO 2 to ≤94%. Three of these had a reduction in SpO 2 to ≤92%, for which all three were admitted to hospital. Modified Roth score and SpO 2 were weakly positively correlated (.31). MRC dyspnoea scale score and SpO 2 were moderately negatively correlated (-.53).

Conclusions

A reduction in SpO 2 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 SpO 2 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.

Article activity feed

  1. ScreenIT

    SciScore for 10.1101/2021.01.03.21249168: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Statistical analysis: Statistical analysis was performed using SPSS Statistics software version 27.11 Continuous variables are presented as mean ± standard deviation (SD).
    SPSS
    suggested: (SPSS, RRID:SCR_002865)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    While we recognise the limitation around the relatively small sample size within this study, there are some interesting findings which should be explored further within large outcome-based clinical trials. For instance, we identified a drop in SpO2 to 92% to be highly predictive for hospital admission. This mirrors the conclusion drawn from a larger observational study delivered in COVID-19 patients following a discharge from A&E, where SpO2 values below 92% were predictive for re-hospitalisation.12 Our study has reinforced the cut-off value of 94% or 93%, as outlined by NHS England to be a trigger for assessment by a healthcare professional, and for an oxygen saturation of 92% or below to be a prompt for urgent admission to hospital.6 Three patients within our study cohort dropped their oxygen saturation to at least 92%. In all cases, it was the drop in oxygen saturation, accompanied by a deterioration in physical condition, which prompted a call to the emergency services, which in two cases was made by the next-of-kin, who incidentally had COVID-19 also. Whilst it is conjecture to speculate whether the oximetry monitoring conferred a mortality and morbidity advantage, it is reassuring that all those admitted to hospital were ultimately discharged from hospital. While the value that the oxygen saturation dropped to was an important indicator, the absolute reduction in SpO2 was also an important sensitiser towards clinical deterioration. For example, in two of the three patie...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Version published to 10.1101/2021.01.03.21249168v1 on medRxiv
  3. Version published to 10.26502/acbr.50170194