Routine blood test may predict increased mortality risk in COVID-19 patients, study finds
Blood samples are seen in this file photo. (Henrik Dolle/Istock.com)
TORONTO -- U.S. scientists say they have identified a routine blood test that could help predict which COVID-19 patients admitted to hospital face a higher risk of becoming critically ill and dying from the virus.
The standardized blood test, known as the red cell distribution width (RDW) test, is typically used to help diagnose medical conditions such as anemia, heart disease and diabetes.
Now, researchers at Massachusetts General Hospital in Boston have found that the RDW test can also be linked to COVID-19 death rates.
"We were surprised to find that one standard test that quantifies the variation in size of red blood cells… was highly correlated with patient mortality, and the correlation persisted when controlling for other identified risk factors like patient age, some other lab tests, and some pre-existing illnesses," the study’s co-author Dr. Jonathan Carlson said in a press release.
The findings were published Wednesday in the journal JAMA Network Open.
The study looked at 1,641 adults diagnosed with SARS-CoV-2, the virus that causes COVID-19, and admitted to one of four hospitals in the Boston area between March 4 and April 28. Before looking for complicated changes in circulating blood cells, the scientists first searched for patterns using currently available blood tests.
"We wanted to help find ways to identify high-risk COVID patients as early and as easily as possible -- who is likely to become severely ill and may benefit from aggressive interventions, and which hospitalized patients are likely to get worse most quickly," senior author Dr. John Higgins said in the release.
The study found that patients who had an RDW value above the normal range when they were admitted to the hospital had a 2.7-times higher risk of dying, with a mortality rate of 31 per cent compared to 11 per cent in patients with normal RDW values.
The study also found a subsequent increase in RDW values after admission was associated with an even higher risk of dying. Researchers say these findings suggest that the RDW could be tracked during hospitalization to help determine whether patients are responding to treatment or getting worse.
The study noted that early reports from China indicated that the body's inflammatory response to the novel coronavirus was "extremely intense" in some patients and very mild in others. Previous work done by the researchers also revealed that certain changes in the numbers and types of blood cells during inflammation are associated with poor health outcomes in patients with diseases including heart disease, cancer, and diabetes.
Researchers said they are now looking into the mechanisms that cause RDW increases in severe COVID-19 cases to better protect those most at risk.
"Such discoveries could point to new treatment strategies or identify better markers of disease severity," co-author Aaron Aguirre said in the release.