High blood viscosity associated with increased death rate in hospitalized COVID-19 patients

A new study found that patients hospitalized with the novel coronavirus (COVID-19), who had a high blood viscosity were significantly more likely to die than patients with a low blood viscosity, suggesting that measuring blood viscosity could predict a COVID-19 patient’s risk of mortality.

The study was published in the Journal of the American College of Cardiology, and led by Robert Rosenson, MD, professor of medicine at the Icahn School of Medicine at Mount Sinai Hospital in New York , as well as director of cardiometabolic disorders for the Mount Sinai Health System.

According to the study, blood viscosity is a measure of blood thickness, and when high, it restricts blood flow to small vessels, increasing the chance of blood clots. While doctors typically conduct related blood tests before diagnosing  a patient and when monitoring a patient’s treatment, generally they do not measure blood viscosity directly. In this study, researchers set out to discover how effective measuring the blood viscosity of a COVID-19 patient would be in predicting their risk of mortality.

Researchers analyzed the records of 5,621 COVID-19 patients from six hospitals within the Mount Sinai Health System between Feb. 27, 2020, and Nov. 27, 2021. Each patient was diagnosed with COVID-19 within 48 hours of hospitalization and followed throughout their time at the hospital.

The study’s results showed that compared to those with a low blood viscosity, COVID-19 patients with a high blood viscosity had a 60 percent higher death rate with blood viscosity measured under high flow conditions, like arteries. In addition, researchers found that patients with a high blood viscosity measured under low flow conditions, such as blood circulation at the smallest blood vessel, had a 32 percent higher mortality rate than those with a low blood viscosity measured in the same conditions.

“This study demonstrates the importance of checking for blood viscosity in COVID-19 patients early in hospital admission, which is easily obtained through routine lab work,” Rosenson said in a statement. “Results can help determine the best treatment course for at-risk patients and help improve outcomes.”