23-29 november 2020
Observe levels of biomarkers so as to anticipate the illness evolution
Mortality rates and the severity of COVID-19 are associated with high levels of cytokines and certain inflammatory biomarkers, molecules that are essential in diagnosis. The cytokines, like Interleuken IL-6, are small immunological proteins produced after infection that remotely regulate the activity of immune cells. As for the biomarker, it is a measurable biological substance linked to infection levels. An example is CRP (C-reactive protein) which is secreted by the liver during inflammatory reactions.
During clinical studies, patients are generally separated into two groups: critical cases and others. To do this we use, for example, the ROX index that provides parameters for respiratory rates and the patient’s oxygenation. One of the difficulties of treatment is that at the present time there is no prognosis tool which can predict whether non-critical patients will remain stable or if they will evolve towards severe respiratory distress. Accurate prediction would allow doctors to prioritize risks and optimize care options.
In order to compensate for this lack, the authors retrospectively analysed the medical details of the first 100 COVID-19 patients (confirmed by PCR technology) admitted to Brigham hospital in the United States during March-April 2020. They sorted patients into 3 groups: “moderate” cases, stable and non-intubated during their hospitalization; “progressive” cases, initially moderate but where respiratory health declined later, requiring intubation; and “severe” cases, unstable and requiring intubation in the 12 hours following their admission. On this basis, they established and compared the profiles of several inflammatory biomarkers in the patients.
The authors confirm the findings of previous studies showing that in severe cases, the levels of CRP and IL-6 are higher than in moderately ill patients. On the other hand, they note that with progressive patients, levels of CRP increase significantly over the first 48 hours following admission, but remain stable in moderately ill patients.
This shows that the behaviour of the biomarkers should be accorded early and careful attention, and not be considered to have fixed and invariable levels as measured when patients are admitted. This provides a simple tool for front-line clinicians that is more reliable than the ROX index to help track respiratory decline and indicate the need to move on to intubation.
As a final step, this study now needs to be confirmed by other hospitals and applied to a wider palette of inflammatory biomarkers.