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Zakai Study Examines Condition that Sidelined Serena Williams

March is Deep-Vein Thrombosis Awareness Month

International tennis star Serena Williams experienced the fright of her life last month when she learned she had developed a potentially fatal blood clot in her lung. Likely the result of a triple-whammy of risk factors – she had undergone two foot surgeries, traveled by air, and is African-American – all of which can lead to the development of a deep-vein thrombosis (DVT) or blood clot in the leg. In Williams’ case, this clot became a pulmonary embolus when pieces of it broke off and traveled to her lungs.

Neil Zakai, M.D., University of Vermont assistant professor of medicine, is currently conducting a study to determine why African-American people have a higher risk of venous thrombosis – a blood clot that forms in a vein.

“We know that African-Americans have an increased risk of venous thrombosis, but a venous thromboembolism (VTE) in someone Serena Williams’ age is unusual,” says Zakai. “In the ‘Reasons for Racial Differences in Venous Thrombosis’ study, we are seeking to understand why African-Americans have a higher incidence of VTE compared to other Americans, whether this is due to an increased prevalence of traditional risk factors, or novel risk factors specific to African-Americans.”

Recent findings from a different, but related study presented by Zakai at the American Society of Hematology annual conference in December 2010 showed that African-Americans had higher rates of some traditional VTE risk factors, such as obesity, but that some VTE risk factors may have different impacts in African-Americans as compared to white Americans. Hypertension and kidney disease appeared to be unique risk factors for venous thrombosis in African-Americans. This study was limited in that less than a quarter of the people were African-American.

Zakai is currently capturing VTE events in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study, a study of more than 30,000 people throughout the U.S., half of whom are African-American.

“African-Americans have been traditionally underrepresented in research studies for a variety of reasons,” says Zakai. “Most studies of venous thrombosis risk factors have been done in Europe or the U.S. in individuals of primarily European ancestry. By combining results from these two studies, we will begin to understand the reasons for the increased risk in African-Americans.”

Zakai’s “Reasons for Racial Differences in Venous Thrombosis” study is being funded by a grant from the National Institutes of Health with money from the American Recovery and Reinvestment Act. UVM has been at the forefront of research in risk factors for venous thrombosis for the past 20 years, advanced by collaborations with investigators from throughout the U.S. and world.