Estimated Sp02/Fio2 ratio to predict mortality in patients with suspected COVID-19 in the Emergency Department: a prospective cohort study

  1. Johannes von Vopelius-Feldt
  2. Daniel Watson
  3. Carla Swanson-Low
  4. James Cameron

Reviewed by

Read the full article

Listed in

Log in to save this article

Abstract

Background This study examined whether the presence and severity of Type 1 Respiratory Failure (T1RF), as measured by the ratio of pulse oximetry to estimated fraction of inspired oxygen (SpO2/eFiO2 ratio), is a predictor of in-hospital mortality in patients presenting to the ED with suspected COVID19 infection. Methods We undertook a prospective observational cohort study of patients admitted to hospital with suspected COVID-19 in a single ED in England. We used univariate and multiple logistic regression to examine whether the presence and severity of T1RF in the ED was independently associated with in-hospital mortality. Results 180 patients with suspected COVID19 infection met the inclusion criteria for this study, of which 39 (22%) died. Severity of T1RF was associated with increased mortality with odds ratios (OR) and 95% confidence intervals of 1.58 (0.49 to 5.14), 3.60 (1.23 to 10.6) and 18.5 (5.65 to 60.8) for mild, moderate and severe T1RF, respectively. After adjusting for age, gender, pre-existing cardiovascular disease, neutrophil-lymphocyte ration (NLR) and estimated glomerular filtration rate (eGFR), the association remained, with ORs of 0.63 (0.13 to 3.03), 3.95 (0.94 to 16.6) and 45.8 (7.25 to 290). The results were consistent across a number of sensitivity analyses. Conclusions Severity of T1RF in the ED is an important prognostic factor of mortality in patients admitted with suspected COVID19 infection. Current prediction models frequently do not include this factor and should be applied with caution. Further large scale research on predictors of mortality in COVID19 infection should include SpO2/eFiO2 ratios or a similar measure of respiratory dysfunction.

Article activity feed

  1. ScreenIT

    SciScore for 10.1101/2020.05.28.20116194: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: The need for research ethics committee (REC) review was waived by the Health Research Authority (HRA) based on the fact that only anonymised data was processed for a COVID-19 related research project.[
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Triage to the assessment area was based on any of the following symptoms: shortness of breath, pyrexia higher than 37.8C or a new persistent cough.
    Triage
    suggested: (TRIAGE, RRID:SCR_016609)

    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:
    Of note, within the limitations of this research, no other vital parameters or blood tests were clearly independently associated with mortality. Results were consistent across different models and sensitivity analyses. Acute lung injury and an ARDS-like picture are the hallmark of COVID-19 infection and a main cause of mortality.[6] This is confirmed by the sobering statistic of patients presenting to the ED with suspected COVID-19 in our study, with mortality rates of 30% and 68% in patients with moderate and severe T1RF, respectively. Importantly, while the mortality rate in patients with no or mild T1RF (10% and 16%, respectively) are significantly lower, patients in these groups were nevertheless at considerable risk of deterioration and death. While our data did not allow for more detailed analysis of the in-hospital course of illness, it would be of value for future research to investigate if the mortality in the no/mild T1RF patient group is due to a later development of an ARDS-type picture or other pathology, such as venous thrombotic events, cardiac complications or multi-organ failure.[16] This would allow targeted monitoring and appropriate escalation of care, as required. A number of previous studies have attempted to predict mortality from COVID-19 infection based on factors measured in ED.[5] Importantly, many of these models do not include the presence or severity of T1RF, which in our study has a strong association with mortality. Clinicians in the ED should ...

    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 10.1101/2020.05.28.20116194v1 on medRxiv