Development and validation of an early warning model for hospitalized COVID-19 patients: a multi-center retrospective cohort study

Jim M. Smit*, Jesse H. Krijthe, Andrei N. Tintu, Henrik Endeman, Jeroen Ludikhuize, Michel E. van Genderen, Shermarke Hassan, Rachida El Moussaoui, Peter E. Westerweel, Robbert J. Goekoop, Geeke Waverijn, Tim Verheijen, Jan G. den Hollander, Mark G. J. de Boer, Diederik A. M. P. J. Gommers, Robin van der Vlies, Mark Schellings, Regina A. Carels, Cees van Nieuwkoop, Sesmu M. ArbousJasper van Bommel, Rachel Knevel, Yolanda B. de Rijke, Marcel J. T. Reinders

*Corresponding author for this work

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Background: Timely identification of deteriorating COVID-19 patients is needed to guide changes in clinical management and admission to intensive care units (ICUs). There is significant concern that widely used Early warning scores (EWSs) underestimate illness severity in COVID-19 patients and therefore, we developed an early warning model specifically for COVID-19 patients.

Methods: We retrospectively collected electronic medical record data to extract predictors and used these to fit a random forest model. To simulate the situation in which the model would have been developed after the first and implemented during the second COVID-19 `wave' in the Netherlands, we performed a temporal validation by splitting all included patients into groups admitted before and after August 1, 2020. Furthermore, we propose a method for dynamic model updating to retain model performance over time. We evaluated model discrimination and calibration, performed a decision curve analysis, and quantified the importance of predictors using SHapley Additive exPlanations values.

Results: We included 3514 COVID-19 patient admissions from six Dutch hospitals between February 2020 and May 2021, and included a total of 18 predictors for model fitting. The model showed a higher discriminative performance in terms of partial area under the receiver operating characteristic curve (0.82 [0.80-0.84]) compared to the National early warning score (0.72 [0.69-0.74]) and the Modified early warning score (0.67 [0.65-0.69]), a greater net benefit over a range of clinically relevant model thresholds, and relatively good calibration (intercept = 0.03 [- 0.09 to 0.14], slope = 0.79 [0.73-0.86]).

Conclusions: This study shows the potential benefit of moving from early warning models for the general inpatient population to models for specific patient groups. Further (independent) validation of the model is needed.

Original languageEnglish
Article number38
Number of pages18
JournalIntensive Care Medicine Experimental
Issue number1
Publication statusPublished - Dec 2022

Bibliographical note

Funding Information:
The authors wish to thank Filip Haegdorens, Ewout Steyerberg, Andrew Vickers and Arash Kia for the interesting discussions on the study topic.

Publisher Copyright:
© 2022, The Author(s).


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