Irish and US scientists have developed a score based on the results of a blood test, that accurately predicts which patients will go on to develop a severe form of COVID-19.

The measurement is called the Dublin-Boston score and it has been developed by researchers at the Royal College of Surgeons in Ireland (RCSI), Dublin's Beaumont Hospital, Harvard University in Massachusetts and the Brigham and Women's Hospital in Boston.

The score can accurately predict how severe an infection will be on day seven after measuring a patient's blood for the first four days. It is hoped that this will help clinicians to make more informed decisions about the best treatment options for their patients.

Until now, there have been no COVID-19-specific prognostic scores to guide clinical decision making.

The blood test measures the levels of two molecules that send messages to the body's immune system and control inflammation. One of these molecules, interleukin (IL)-6, is pro-inflammatory, and the other, IL-10, is anti-inflammatory.

The levels of both of these molecules are altered in patients with severe COVID-19.

Based on the changes in the ratio of these two molecules over time, the researchers developed a point system where each one-point increase was associated with a 5.6 times increased odds for a more severe outcome.

The score uses the ratio of IL-6 to IL-10 because it was much more accurate than measuring the change in IL-6 alone.

According to the study's senior author, Beaumont consultant and RCSI professor of medicine, Prof Gerry McElvaney, the Dublin-Boston score is easily calculated and can be applied to all hospitalised COVID-19 patients.

"More informed prognosis could help determine when to escalate or de-escalate care, a key component of the efficient allocation of resources during the current pandemic.

"The score may also have a role in evaluating whether new therapies designed to decrease inflammation in COVID-19 actually provide benefit," he explained.

Details of the research which led to the development of the Dublin-Boston score are published in the journal, EBioMedicine.