High blood viscosity can predict higher risk of death in hospitalized COVID-19 patients

Study Title: "Association of Blood Viscosity with Mortality among Patients Hospitalized with COVID-19"

Journal: Journal of the American College of Cardiology - *Embargoed until July 18, 2 pm EDT

Author: Robert Rosenson, MD, Professor of Medicine (Cardiology) at the Icahn School of Medicine at Mount Sinai and Director of Cardiometabolic Disorders for the Mount Sinai Health System

Bottom Line:  Patients hospitalized with COVID-19 with high estimated blood viscosity are at higher risk of death from complications. High blood viscosity impairs flow to small vessels and increases the risk of blood clots. This measure of blood thickness can be used as a predictor of mortality.

Why Study Is Unique: This large-scale study is the first to evaluate blood viscosity in the prediction of mortality in COVID-19 patients. A simple calculation of blood viscosity was more robust in the identification of hospitalized patients at risk for dying from COVID-19 complications when compared to common measures of inflammation and the blood clotting biomarker D-dimer.

Why Study Is Important:  Doctors typically measure hematocrit and globulins (difference between total protein and albumin) in all patients for diagnosis and monitoring treatment of hospitalized patients; however, they do not measure blood viscosity directly. A validated estimate of blood viscosity can be derived from the hematocrit and globulins. In this study the estimate of blood viscosity was more strongly associated with mortality in COVID-19 patients than other commonly used risk stratification measures. This is an easy calculation that could be added to electronic medical records or lab forms and can improve chances for survival in hospitalized COVID-19 patients.

How Study Was Conducted: Researchers looked at records of 5,621 COVID-19 patients from six hospitals in the Mount Sinai Health System between February 27, 2020, and November 27, 2021. All had clinical and laboratory-verified diagnoses of COVID 19 and were identified within 48 hours of hospitalization and followed until hospital discharge or death.

What the Study Found: Hospitalized patients who had high blood viscosity had a 60 percent higher death rate with blood viscosity measured under high flow conditions such as the arteries and 32 percent higher mortality with blood viscosity measured at low flow such as the microcirculation (blood circulation in the smallest vessels), than patients with a low blood viscosity.

What This Means for Physicians/Patients:  Blood viscosity is elevated by acute phase reactants (fibrinogen, macroglobulins) that have been associated with acute COVID-19 infections. Blood viscosity is an integrated measure of these acute phase reactants and the cellular components that can increase during infection. When the blood viscosity is high, physicians may consider therapeutic heparin for patients, hydration, or intensification of glucocorticoids to lessen the severity of the acute phase response to COVID-19.

Quotes: “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. Results can help determine the best treatment course for at-risk patients and help improve outcomes,” says Dr. Rosenson. “We are currently investigating the effects of therapeutic heparin to reduce the risk of complications during acute COVID-19 infections, which may greatly benefit those with high blood viscosity.”

About Mount Sinai Health System 

Mount Sinai Health System is one of the largest academic medical systems in the New York metro area, with more than 43,000 employees working across eight hospitals, over 400 outpatient practices, nearly 300 labs, a school of nursing, and a leading school of medicine and graduate education. Mount Sinai advances health for all people, everywhere, by taking on the most complex health care challenges of our time — discovering and applying new scientific learning and knowledge; developing safer, more effective treatments; educating the next generation of medical leaders and innovators; and supporting local communities by delivering high-quality care to all who need it.  

Through the integration of its hospitals, labs, and schools, Mount Sinai offers comprehensive health care solutions from birth through geriatrics, leveraging innovative approaches such as artificial intelligence and informatics while keeping patients’ medical and emotional needs at the center of all treatment. The Health System includes approximately 7,300 primary and specialty care physicians; 13 joint-venture outpatient surgery centers throughout the five boroughs of New York City, Westchester, Long Island, and Florida; and more than 30 affiliated community health centers. We are consistently ranked by U.S. News & World Report's Best Hospitals, receiving high "Honor Roll" status, and are highly ranked: No. 1 in Geriatrics, and top 20 in Cardiology/Heart Surgery, Diabetes/Endocrinology, Gastroenterology/GI Surgery, Neurology/Neurosurgery, Orthopedics, Pulmonology/Lung Surgery, Rehabilitation, and Urology. New York Eye and Ear Infirmary of Mount Sinai is ranked No. 12 in Ophthalmology. U.S. News & World Report’s “Best Children’s Hospitals” ranks Mount Sinai Kravis Children's Hospital among the country’s best in several pediatric specialties. The Icahn School of Medicine at Mount Sinai is one of three medical schools that have earned distinction by multiple indicators: It is consistently ranked in the top 20 by U.S. News & World Report's "Best Medical Schools," aligned with a U.S. News & World Report "Honor Roll" Hospital, and top 20 in the nation for National Institutes of Health funding and top 5 in the nation for numerous basic and clinical research areas. Newsweek’s “The World’s Best Smart Hospitals” ranks The Mount Sinai Hospital as No. 1 in New York and in the top five globally, and Mount Sinai Morningside in the top 20 globally. For more information, visit https://www.mountsinai.org or find Mount Sinai on Facebook, Twitter, and YouTube. 

###