Scientists at Washington University School of Medicine have shown that a rapid blood test can predict which COVID-19 patients are at highest risk of severe complications or death.

The study, published in JCI Insight, involved almost 100 patients newly admitted to the hospital with COVID-19.

The blood test measures levels of mitochondrial DNA, a unique type of DNA molecule that normally resides inside the energy factories of cells. Mitochondrial DNA spilling out of cells and into the bloodstream is a sign that a particular type of violent cell death is taking place in the body.

Co-senior author Andrew E. Gelman said: “Doctors need better tools to evaluate the status of COVID-19 patients as early as possible because many of the treatments, such as monoclonal antibodies, are in short supply, and we know that some patients will get better without intensive treatments.

“There’s so much we still don’t understand about this disease. In particular, we need to understand why some patients, irrespective of their ages or underlying health in some cases, go into this hyperinflammatory death spiral.

“Our study suggests that tissue damage may be one cause of this spiral, since the mitochondrial DNA that is released is itself an inflammatory molecule.”

The researchers evaluated 97 patients with COVID-19 at Barnes-Jewish Hospital, measuring their mitochondrial DNA levels on the first day of their hospital stays. They found that mitochondrial DNA levels were much higher in patients who eventually were admitted to the ICU, intubated or died.

The researchers found this association held independently of a patient’s age, sex and underlying health conditions.

The team have said the test could serve as a way to predict disease severity, as well as a tool to better design clinical trials, identifying patients who might benefit from specific investigational treatments. They also said they would like to evaluate whether the test could serve as a way to monitor the effectiveness of new therapies.

Co-senior author Hrishikesh S. Kulkarni said: “We will need larger trials to verify what we found in this study, but if we could determine in the first 24 hours of admission whether a patient is likely to need dialysis or intubation or medication to keep their blood pressure from dropping too low, that would change how we triage the patient, and it might change how we manage them much earlier in the disease course.”