Prognostic accuracy of triage tools for adults with suspected COVID-19 in a prehospital setting: an observational cohort study

  1. Carl Marincowitz
  2. Laura Sutton
  3. Tony Stone
  4. Richard Pilbery
  5. Richard Campbell
  6. Benjamin Thomas
  7. Janette Turner
  8. Peter A Bath
  9. Fiona Bell
  10. Katie Biggs
  11. Madina Hasan
  12. Frank Hopfgartner
  13. Suvodeep Mazumdar
  14. Jennifer Petrie
  15. Steve Goodacre

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Abstract

Tools proposed to triage patient acuity in COVID-19 infection have only been validated in hospital populations. We estimated the accuracy of five risk-stratification tools recommended to predict severe illness and compared accuracy to existing clinical decision making in a prehospital setting.

Methods

An observational cohort study using linked ambulance service data for patients attended by Emergency Medical Service (EMS) crews in the Yorkshire and Humber region of England between 26 March 2020 and 25 June 2020 was conducted to assess performance of the Pandemic Respiratory Infection Emergency System Triage (PRIEST) tool, National Early Warning Score (NEWS2), WHO algorithm, CRB-65 and Pandemic Medical Early Warning Score (PMEWS) in patients with suspected COVID-19 infection. The primary outcome was death or need for organ support.

Results

Of the 7549 patients in our cohort, 17.6% (95% CI 16.8% to 18.5%) experienced the primary outcome. The NEWS2 (National Early Warning Score, version 2), PMEWS, PRIEST tool and WHO algorithm identified patients at risk of adverse outcomes with a high sensitivity (>0.95) and specificity ranging from 0.3 (NEWS2) to 0.41 (PRIEST tool). The high sensitivity of NEWS2 and PMEWS was achieved by using lower thresholds than previously recommended. On index assessment, 65% of patients were transported to hospital and EMS decision to transfer patients achieved a sensitivity of 0.84 (95% CI 0.83 to 0.85) and specificity of 0.39 (95% CI 0.39 to 0.40).

Conclusion

Use of NEWS2, PMEWS, PRIEST tool and WHO algorithm could improve sensitivity of EMS triage of patients with suspected COVID-19 infection. Use of the PRIEST tool would improve sensitivity of triage without increasing the number of patients conveyed to hospital.

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  1. Version published to 10.1136/emermed-2021-211934
  2. ScreenIT

    SciScore for 10.1101/2021.07.27.21261031: (What is this?)

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

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    All analyses were based on assessment during the index EMS attendance and completed with SAS v9.4.
    SAS
    suggested: (SASqPCR, RRID:SCR_003056)

    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:
    Strengths and limitations: Previous evaluations of triage tool accuracy and prognostic COVID-19 prognostic research in the pre-hospital setting, are limited by only including patients who were subsequently admitted to hospital.22-25 This is the first evaluation to use a large cohort of patients identified from routinely collected EMS records and linked to nationally collected, patient-level, healthcare data to provide robust outcome data for all patients including those not conveyed to hospital. We had low rates of missing data in the variables used in the triage tools assessed (Table 1). We also assessed the performance of triage tools in a cohort of patients with suspected infection which, in the absence of accurate universally available rapid COVID-19 diagnostic tests, reflects the population which EMS staff must clinically triage. Most existing research either aimed to determine if patients with suspected infection have COVID-19, or to risk stratify patients with confirmed infection in a hospital setting.26 Our evaluation of triage tool accuracy is limited to a single ambulance service, albeit one covering a large population across the North of England, so the results may not be generalisable to other healthcare settings. Other ambulance services may serve populations with a different risk-profile, provide different types of EMS response or have different thresholds and guidelines regarding when to convey patients to hospital. The population used is likely to be have simi...

    Results from TrialIdentifier: We found the following clinical trial numbers in your paper:

    IdentifierStatusTitle
    ISRCTN28342533NANA

    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.

    Results from scite Reference Check: We found no unreliable references.

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  3. Version published to 10.1101/2021.07.27.21261031v1 on medRxiv