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Validation of oxygen saturations measured in the community by emergency medical services as a marker of clinical deterioration in patients with confirmed COVID-19: a retrospective cohort study

Validation of oxygen saturations measured in the community by emergency medical services as a marker of clinical deterioration in patients with confirmed COVID-19: a retrospective cohort study
Validation of oxygen saturations measured in the community by emergency medical services as a marker of clinical deterioration in patients with confirmed COVID-19: a retrospective cohort study
Objectives: to evaluate oxygen saturation and vital signs measured in the community by emergency medical services (EMS) as clinical markers of COVID-19-positive patient deterioration.

Design: a retrospective data analysis.

Setting: patients were conveyed by EMS to two hospitals in Hampshire, UK, between 1 March 2020 and 31 July 2020.

Participants: a total of 1080 patients aged ≥18 years with a COVID-19 diagnosis were conveyed by EMS to the hospital.

Primary and secondary outcome measures: the primary study outcome was admission to the intensive care unit (ICU) within 30 days of conveyance, with a secondary outcome representing mortality within 30 days of conveyance. Receiver operating characteristic (ROC) analysis was performed to evaluate, in a retrospective fashion, the efficacy of different variables in predicting patient outcomes.

Results: vital signs measured by EMS staff at the first point of contact in the community correlated with patient 30-day ICU admission and mortality. Oxygen saturation was comparably predictive of 30-day ICU admission (area under ROC (AUROC) 0.753; 95% CI 0.668 to 0.826) to the National Early Warning Score 2 (AUROC 0.731; 95% CI 0.655 to 0.800), followed by temperature (AUROC 0.720; 95% CI 0.640 to 0.793) and respiration rate (AUROC 0.672; 95% CI 0.586 to 0.756).

Conclusions: initial oxygen saturation measurements (on air) for confirmed COVID-19 patients conveyed by EMS correlated with short-term patient outcomes, demonstrating an AUROC of 0.753 (95% CI 0.668 to 0.826) in predicting 30-day ICU admission. We found that the threshold of 93% oxygen saturation is prognostic of adverse events and of value for clinician decision-making with sensitivity (74.2% CI 0.642 to 0.840) and specificity (70.6% CI 0.678 to 0.734).
2044-6055
Inada-Kim, Matthew
80f1afd6-cc55-4dd5-9d5b-a87567054904
Chmiel, Francis P.
2de259aa-a5eb-460c-bfbf-8b44ed02e2bd
Boniface, Michael
f30bfd7d-20ed-451b-b405-34e3e22fdfba
Burns, Daniel
40b9dc88-a54a-4365-b747-4456d9203146
Pocock, Helen
ba8e097b-d073-46b2-9669-96e8e4689abc
Black, John
c9cf4036-ec61-4d6c-bf17-58cf338fdf06
Deakin, Charles
560d993b-bbc9-4548-9990-272ed18a011d
Inada-Kim, Matthew
80f1afd6-cc55-4dd5-9d5b-a87567054904
Chmiel, Francis P.
2de259aa-a5eb-460c-bfbf-8b44ed02e2bd
Boniface, Michael
f30bfd7d-20ed-451b-b405-34e3e22fdfba
Burns, Daniel
40b9dc88-a54a-4365-b747-4456d9203146
Pocock, Helen
ba8e097b-d073-46b2-9669-96e8e4689abc
Black, John
c9cf4036-ec61-4d6c-bf17-58cf338fdf06
Deakin, Charles
560d993b-bbc9-4548-9990-272ed18a011d

Inada-Kim, Matthew, Chmiel, Francis P., Boniface, Michael, Burns, Daniel, Pocock, Helen, Black, John and Deakin, Charles (2024) Validation of oxygen saturations measured in the community by emergency medical services as a marker of clinical deterioration in patients with confirmed COVID-19: a retrospective cohort study. BMJ Open, 14 (1), [e067378]. (doi:10.1136/bmjopen-2022-067378).

Record type: Article

Abstract

Objectives: to evaluate oxygen saturation and vital signs measured in the community by emergency medical services (EMS) as clinical markers of COVID-19-positive patient deterioration.

Design: a retrospective data analysis.

Setting: patients were conveyed by EMS to two hospitals in Hampshire, UK, between 1 March 2020 and 31 July 2020.

Participants: a total of 1080 patients aged ≥18 years with a COVID-19 diagnosis were conveyed by EMS to the hospital.

Primary and secondary outcome measures: the primary study outcome was admission to the intensive care unit (ICU) within 30 days of conveyance, with a secondary outcome representing mortality within 30 days of conveyance. Receiver operating characteristic (ROC) analysis was performed to evaluate, in a retrospective fashion, the efficacy of different variables in predicting patient outcomes.

Results: vital signs measured by EMS staff at the first point of contact in the community correlated with patient 30-day ICU admission and mortality. Oxygen saturation was comparably predictive of 30-day ICU admission (area under ROC (AUROC) 0.753; 95% CI 0.668 to 0.826) to the National Early Warning Score 2 (AUROC 0.731; 95% CI 0.655 to 0.800), followed by temperature (AUROC 0.720; 95% CI 0.640 to 0.793) and respiration rate (AUROC 0.672; 95% CI 0.586 to 0.756).

Conclusions: initial oxygen saturation measurements (on air) for confirmed COVID-19 patients conveyed by EMS correlated with short-term patient outcomes, demonstrating an AUROC of 0.753 (95% CI 0.668 to 0.826) in predicting 30-day ICU admission. We found that the threshold of 93% oxygen saturation is prognostic of adverse events and of value for clinician decision-making with sensitivity (74.2% CI 0.642 to 0.840) and specificity (70.6% CI 0.678 to 0.734).

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More information

Accepted/In Press date: 27 November 2023
e-pub ahead of print date: 2 January 2024
Published date: 2 January 2024
Additional Information: Publisher Copyright: © Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.

Identifiers

Local EPrints ID: 489212
URI: http://eprints.soton.ac.uk/id/eprint/489212
ISSN: 2044-6055
PURE UUID: 9c8252cc-5ae4-43bd-bbbb-db2fa3f8a063
ORCID for Michael Boniface: ORCID iD orcid.org/0000-0002-9281-6095
ORCID for Daniel Burns: ORCID iD orcid.org/0000-0001-6976-1068

Catalogue record

Date deposited: 18 Apr 2024 16:30
Last modified: 06 Jun 2024 01:59

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Contributors

Author: Matthew Inada-Kim
Author: Francis P. Chmiel
Author: Daniel Burns ORCID iD
Author: Helen Pocock
Author: John Black
Author: Charles Deakin

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