Routine blood test predicts increased mortality risk in COVID-19 patients

A standard test that assesses blood cells can identify which patients who are admitted to the hospital with the novel coronavirus (COVID-19) face a high risk of becoming critically ill and dying, according to a new discovery a team of investigators at Massachusetts General Hospital (MGH) based in the MGH Center for Systems Biology and described in JAMA Network Open.

Early reports from China indicated that the body's inflammatory response was extremely intense in some patients and very mild in others, the researchers said. the group's previous work revealed that certain changes in the numbers and types of blood cells during inflammation are associated with poor health outcomes in patients with diseases such as heart disease, cancer, and diabetes.

The analysis included all adults diagnosed with SARS-CoV-2 infection and admitted to one of four hospitals in the Boston area between March 4 and April 28, 2020. Before looking for complicated changes in circulating blood cells in the 1,641 patients included in the study, the researchers first searched for patterns using currently available blood tests that are routinely performed.

A standard test that quantifies the variation in size of red blood cells, red cell distribution width (RDW), was 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 researchers said. Patients who had RDW values 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 percent compared with 11 percent in patients with normal RDW values, according to the study. Additionally, a subsequent increase in RDW after admission was associated with an even higher risk of dying, indicating that RDW could be tracked during hospitalization to help determine whether patients are responding to treatment or getting worse.

The investigators are currently seeking to uncover the mechanisms that cause RDW elevations in severe COVID-19 cases, which the researchers said could point to new treatment strategies or improved markers of disease severity.

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