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WHO Ordinal Scale and Inflammation Risk Categories in COVID-19. Comparative Study of the Severity Scales
Manuel Rubio-Rivas1, José María Mora-Luján2, Francesc Formiga2
1Department of Internal Medicine, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, University of Barcelona, Barcelona, Spain. mrubio@bellvitgehospital.cat.
Insights
A new hybrid severity scale for COVID-19 patients improves mortality prediction compared to the WHO scale. This enhanced model offers a more informative and representative assessment for hospitalized individuals.
Area of Science:
- Infectious Diseases
- Clinical Medicine
- Public Health
Background:
- The World Health Organization (WHO) ordinal severity scale is a standard tool for assessing COVID-19 severity and guiding clinical trials.
- Limitations exist in the WHO scale's predictive accuracy for mortality and guiding treatment decisions.
- Accurate severity grading is crucial for managing hospitalized COVID-19 patients and optimizing resource allocation.
Purpose of the Study:
- To compare the predictive performance of the WHO ordinal severity scale, an inflammation-based model, and a novel hybrid model for in-hospital mortality in COVID-19 patients.
- To develop and validate a new, more accurate severity grading scale for hospitalized COVID-19 patients.
- To assess the clinical utility of different severity classification systems in a large patient cohort.
Main Methods:
- Retrospective cohort study including 17,225 hospitalized COVID-19 patients from March 2020 to May 2021.
- Data sourced from the nationwide SEMI-COVID-19 Registry.
- Comparison of three models: WHO ordinal scale, inflammation grades model, and a proposed hybrid model, with in-hospital mortality as the primary outcome.
Main Results:
- The hybrid model demonstrated superior predictive performance for in-hospital mortality, achieving an Area Under the Curve (AUC) of 0.871.
- Analysis revealed significant differences in in-hospital mortality across WHO ordinal scale categories (p<0.001).
- The proposed combined ordinal scale showed improved risk stratification compared to the individual models.
Conclusions:
- A novel hybrid severity grading scale for hospitalized COVID-19 patients is proposed, offering enhanced informativeness and predictive power.
- This new scale is considered the most representative and predictive tool for COVID-19 patients evaluated to date.
- The findings suggest that the new hybrid scale can significantly improve the management and outcomes of severe COVID-19 cases.
Background:
The WHO ordinal severity scale has been used to predict mortality and guide trials in COVID-19. However, it has its limitations.
Objective:
The present study aims to compare three classificatory and predictive models: the WHO ordinal severity scale, the model based on inflammation grades, and the hybrid model.
Design:
Retrospective cohort study with patient data collected and followed up from March 1, 2020, to May 1, 2021, from the nationwide SEMI-COVID-19 Registry. The primary study outcome was in-hospital mortality. As this was a hospital-based study, the patients included corresponded to categories 3 to 7 of the WHO ordinal scale. Categories 6 and 7 were grouped in the same category.
Key Results:
A total of 17,225 patients were included in the study. Patients classified as high risk in each of the WHO categories according to the degree of inflammation were as follows: 63.8% vs. 79.9% vs. 90.2% vs. 95.1% (p<0.001). In-hospital mortality for WHO ordinal scale categories 3 to 6/7 was as follows: 0.8% vs. 24.3% vs. 45.3% vs. 34% (p<0.001). In-hospital mortality for the combined categories of ordinal scale 3a to 5b was as follows: 0.4% vs. 1.1% vs. 11.2% vs. 27.5% vs. 35.5% vs. 41.1% (p<0.001). The predictive regression model for in-hospital mortality with our proposed combined ordinal scale reached an AUC=0.871, superior to the two models separately.
Conclusions:
The present study proposes a new severity grading scale for COVID-19 hospitalized patients. In our opinion, it is the most informative, representative, and predictive scale in COVID-19 patients to date.
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