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The ROX index has greater predictive validity than NEWS2 for deterioration in Covid-19

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Emma Prower, David Grant, Alessandra Bisquera, Cormac P. Breen, Luigi Camporota, Maja Gavrilovski, Megan Pontin, Abdel Douiri, Guy W. Glover

Original languageEnglish
Article number100828
PublishedMay 2021

Bibliographical note

Funding Information: We wish to acknowledge the support of Leah Evans, BS, and Kathleen Merkley, DNP, APRN, ANP, of Health Catalyst, Inc. Salt Lake City, Utah for developing the Health Catalyst? Data Operating System (DOS?) utilised for this study. We would also like to acknowledge all of the clinicians and support staff who cared for patients during the COVID-19 pandemic. This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. Individual participant data that underlie the results reported in this article, after de-identification (text, tables, figures, and appendices), an associated data dictionary and the study protocol is available from the corresponding author, immediately following publication and with no end date. This will be made available to researchers who provide a methodologically sound proposal to achieve the aims of the proposal. Please contact, Emma Prower: conceptualisation, methodology, writing ? original draft; David Grant: conceptualisation, methodology, validation, data curation, writing ? review and editing; Alessandra Bisquera: formal analysis, data curation, data visualisation, writing ? review and editing; Cormac Breen: supervision, project administration; writing ? review and editing; Luigi Camporota: conceptualisation, methodology; writing ? review and editing; Maja Gavrilovski: conceptualisation, writing ? review and editing; Meghan Pontin: conceptualisation, project administration, writing ? review and editing; Abdel Douri: formal analysis, data curation, data visualisation, writing ? review and editing; Guy Glover: conceptualisation, methodology, writing ? review and editing. David Grant, Alessandra Bisquera and Guy Glover have verified the underlying data. All authors have read and finally approved the version being submitted. All authors confirm that they had full access to all the data in the study and accept responsibility to submit for publication Funding: This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. Publisher Copyright: © 2021 The Authors Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

King's Authors


Background: Patients admitted to hospital with Covid-19 are at risk of deterioration. The National Early Warning Score (NEWS2) is widely recommended, however it's validity in Covid-19 is not established and indices more specific for respiratory failure may be more appropriate. We aim to describe the physiological antecedents to deterioration, test the predictive validity of NEWS2 and compare this to the ROX index ([SpO2/FiO2]/respiratory rate). Method: A single centre retrospective cohort study of adult patients who were admitted to a medical ward, between 1/3/20 and 30/5/20, with positive results for SARS-CoV-2 RNA. Physiological observations and the NEWS2 were extracted and analysed. The primary outcome was a composite of cardiac arrest, unplanned critical care admission or death within 24 hours. A generalized linear model was used to assess the association of physiological values, NEWS2 and ROX with the outcome. Findings: The primary outcome occurred in 186 patients (26%). In the preceding 24 hours, deterioration was most marked in respiratory parameters, specifically in escalating oxygen requirement; tachypnoea was a late sign, whilst cardiovascular observations remained stable. The area under the receiver operating curve was 0.815 (95% CI 0.804–0.826) for NEWS2 and 0.848 (95% CI 0.837–0.858) for ROX. Applying the optimal level of ROX, the majority of patients triggered four hours earlier than with NEWS2 of 5. Interpretation: NEWS2 may under-perform in Covid-19 due to intrinsic limitations of the design and the unique pathophysiology of the disease. A simple index utilising respiratory parameters can outperform NEWS2 in predicting the occurrence of adverse events.

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