A new Irish study has found that elevated levels of a particular marker in the blood are linked to poorer outcomes for people who have been hospitalised as a result of COVID-19.

The findings may help doctors to identify COVID patients who are at high risk of developing certain complications.

The study, which was led by researchers from the Royal College of Surgeons in Ireland (RCSI), focuses on the blood marker, con Willebrand Factor propeptide. Those with higher levels of this marker are more at risk of developing severe thrombotic (blood clotting) and respiratory complications.

The study helps doctors to understand why patients with COVID-19 develop blood clotting abnormalities that can trigger micro-clot development in the lungs. Previous research has found that the development of these micro-clots can lead to a poorer prognosis for patients and an increased risk requiring intensive care.

This study links the formation of these micro-clots to elevated blood levels of the von Willebrand Factor propeptide, which is already an established blood marker for damage to the endothelial cells lining the blood vessels in the body.

Acute damage of these cells results in the rapid release of von Willebrand Factor propeptide, but also initiates clot formation and inflammation.

The researchers observed that patients with the most severe COVID-19, or those who died as a result of it, had the highest levels of this blood marker. This indicates that levels of the marker may be predictive of poor prognosis and outcome in patients with the virus.

"We have previously established that abnormal blood clotting and the development of micro-clots within the lungs contributes to a greater risk of a poorer prognosis and intensive care admission for Irish patients with COVID-19.

"The mechanisms through which COVID-19 triggers the formation of these micro-clots, however, has been puzzling doctors throughout the world. This research now critically helps us to more clearly understand these mechanisms," explained Prof James O'Donnell, a consultant haematologist and director of the RCSI's Irish Centre for Vascular Biology.

According to the study's co-senior author, Dr Jamie O'Sullivan, of the Irish Centre for Vascular Biology, these findings provide "further insight into the marked and sustained damage to the cells lining the blood vessels in patients with severe COVID-19 and how this may contribute to thrombotic complications".

The study also involved researchers from Beaumont Hospital, St James's Hospital, Trinity College Dublin, St Vincent's University Hospital and our Lady's Children's Hospital in Crumlin.

Details of the findings are published in the British Journal of Haematology.