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Patients affected by COVID-19 should be treated according to the severity of their disease. However, not all key national or international organisations define severity in the same way. This imprecision in severity assessment compromises the validity of some therapeutic recommendations. Using individual patient data would better guide and improve therapeutic recommendations for COVID-19.

Two health care workers in PPE on a ward

WHO's guidelines for the treatment of COVID-19 are based on the combined analyses of published randomised control trials (RCTs), using statistical methods that allow for the comparison of various treatments between studies.

IDDO researchers reviewed 81 studies included in the WHO COVID-19 analysis and compared their severity classifications with those used by another international COVID network. The two were the same in only 35% of trials. Of the RCTs evaluated, 69% were considered by the WHO group to include patients with a range of severities. The distribution of disease severities within these groups usually could not be determined, and data on the duration of illness and/or oxygen saturation values were often missing.

The published literature contains a wide variety of COVID-19 severity threshold criteria, definitions and categories. Many of these are arbitrary and to add to the confusion, during the course of the pandemic some of the definitions were changed. Often, the key measures of severity were not reported at all and when they were, they were frequently incomplete or ambiguous.

This imprecision in severity assessment compromises the validity of some therapeutic recommendations. Crucially, it shows that the extrapolation of “lack of therapeutic benefit” shown in hospitalised severely-ill patients on respiratory support to ambulant, mildly-ill patients should not be done. To address these issues, the researchers recommend using individual patient data (IPD) to guide and improve therapeutic recommendations for COVID-19.

The full story is available on the IDDO website

Read the publication 'Definitions matter: Heterogeneity of COVID-19 disease severity criteria and incomplete reporting compromise meta-analysis' on the PLOS website

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