Researchers have reported that a series of biomarkers, or biological signals, associated with white blood cell activation and obesity can predict severe outcomes in Covid-19 patients.
The findings, published in the journal Blood Advances, indicated that five proteins (resistin, lipocalin-2, HGF, IL-8, and G-CSF) that are associated with neutrophils, a type of white blood cell, were elevated in the Covid-19 patients who later became critically ill.
Many of these proteins had previously been associated with obesity but not with Covid-19 or other viral illnesses, the researchers said.
"Patients with high levels of these markers were much more like to require care in the intensive care unit, require ventilation, or die due to their Covid-19," said lead author Hyung Chun from the Yale University.
Previously, a few laboratory studies had identified possible indicators of severe Covid-19, including D-dimer levels, a measure of blood coagulation, and levels of proteins known as cytokines, which are released as part of inflammatory responses in the body.
However, until now, no laboratory marker could predict which patients with Covid-19 would eventually become critically ill prior to showing clinical signs and symptoms of severe disease.
For the new study, the researchers used proteomic profiling — a screen for multiple proteins within the blood — to analyze samples taken from 100 patients who would go on to experience different levels of Covid-19 severity.
In all cases, the blood samples were collected on the patients' first day of admission. The researchers also analyzed clinical data for over 3,000 additional patients with Covid-19.
Notably, the elevated neutrophil biomarkers for patients who would go on to experience more serious symptoms were evident before those symptoms appeared.
All Covid-19 patients who were admitted or transferred to the ICU had elevated neutrophil activation markers, while these biomarkers remained low for patients who never developed severe illness. None of the patients with lower neutrophil biomarker levels died.
Having early knowledge of these indicators could significantly improve patient treatment, the researchers said.