Why Black Populations Are at Higher Risk for DVT

Medically Reviewed by Jennifer Robinson, MD on April 27, 2022
Written by Susan Bernstein
7 min read

Black people are at higher risk for deep vein thrombosis (DVT) than people of other races. Black people have 30% to 60% higher rates of DVT than white people.

DVT is also called venous thromboembolisms (VTEs). About 1 or 2 out of every 1,000 Americans develop a blood clot each year. DVTs may cause up to 100,000 deaths in America each year.

Black people have a higher risk of blood clots no matter their gender or age. If you’re Black, you’re also at higher risk for pregnancy-associated DVT and pulmonary embolism (PEs), a potentially life-threatening complication after a blood clot.

Some research shows that Black people are three times more likely than white people to have a fatal PE outside of the hospital. Deadly PEs tend to happen to Black people at an earlier age than white people, or an average of 9 years younger.

One large study of American adults found that Black people had the highest rate of newly developed DVT, followed by non-Hispanic whites, then Native Americans, Hispanics, and Asian/Pacific Islanders.

However, non-Hispanic whites had the highest rates of death from a blood clot in the study, followed by Blacks, Native Americans, and Asian/Pacific Islanders, while Hispanics had the lowest rates of death from DVT.

Why are Black people at greater risk for DVT than people of other races? There are several possible reasons.

Family history/genetics. All people are at higher risk of DVT if they have a parent and/or sibling who’s had a blood clot in the past. Black people are equally as likely to have a family history of DVT as white people.

Black populations have higher rates of one genetic trait called hemoglobin S, or the sickle cell trait. Up to 8% of Black people may have this genetic sickle cell trait. Sickle cell disease caused by this trait is rare, but Black people with the trait (but not active disease) are at a nearly twofold higher risk of clots and nearly a fourfold higher risk of pulmonary embolism. People with sickle cell disease often show signs of overactive blood clotting, and they’re also at higher risk of pregnancy-associated blood clots.

Black people also are more likely to have other genetic mutations that increase the risk of blood clots, including factor VIII and von Willebrand factor. Two other genetic traits that may increase clotting activity in your blood, plasma D-dimer and plasmin antiplasmin complexes, are also more common in Black populations. It’s hard to say exactly how these genetic factors play a role in DVT.

In 2016, a study in the journal Blood found that three genetic variants on chromosome 20 that are linked to a higher DVT risk are more common in Black populations. This new finding may help doctors identify who’s at greater risk for blood clots.

Chronic health conditions. Black people who have blood clots tend to be more likely than whites to also have chronic health problems like high blood pressure, diabetes, or chronic kidney disease (CKD). Black people who don’t have DVT also have higher rates of these health conditions, so it’s not clear what role they play in blood clot risk.

  • Metabolic syndrome. Another big risk factor for recurring blood clots, metabolic syndrome isn’t a disease, but happens when you have several chronic health problems, like obesity, high blood pressure, high blood sugar, and high cholesterol. Metabolic syndrome is very common among Black people, especially Black women. In one study of 151,000 people with DVT, 68% also had at least one of the conditions that make up metabolic syndrome.
  • Obesity. Black people have higher rates of obesity than people of other races. But this doesn’t explain why Hispanic people, who also have high rates of obesity, have lower rates of DVT. Genes and chronic health conditions like obesity may be part of a complex mix of factors that affect blood clot risk.
  • Heart disease risk factors. Black people tend to have higher rates of other heart-related health problems than whites in older age, such as strokes, coronary artery disease, or heart failure. These conditions put a lot of pressure on your blood vessels, so they likely increase the risk of DVT among Black people compared with white people.
  • Lupus, or Systemic Lupus Erythematosus. Far more common among Black women and all Black people than in other populations, lupus is a serious autoimmune disease that can cause chronic inflammation in your body. DVT frequently happens in people with lupus. One reason may be that many people with lupus have high levels of antiphospholipid antibodies that cause your blood to form clots.
  • Fibrinogen. Black people may have higher levels of fibrinogen, a protein, in their blood compared to white people. High fibrinogen may be linked to increased DVT risk, but it may not be a strong or clear risk factor.

Blood testing can show if you have certain risk factors for DVT, but normal ranges for these proteins may be different for Black people compared with other racial and ethnic groups. Black people who tested negative for these factors may still develop blood clots, so more sensitive tests are needed.

Blood clots after surgery. Having surgery increases your risk of a blood clot. Among U.S. adults, Black people have the highest risk of a DVT after they’ve had surgery, followed by white people or people of European descent, Hispanics, and then Asian Americans.

Access to care. There may be some differences between the type of treatments prescribed for Black people who have a PE compared with white people. They may be less likely to receive life-saving treatments like catheter-based surgery or placement of an inferior vena cava filter device.

Black people who have a blood clot that causes a PE tend to be admitted to the hospital in a more serious condition than white people. Unequal access to quality care or treatment options may be causing this, but DVT risk is due to a mix of health factors. Black people with DVT and PEs may have more aggressive disease, possibly because of genetic mutations that increase blood clotting. Overall, Black people with heart disease are less likely than white people to get potentially life-saving, advanced treatments.

Smoking/secondhand smoke. Black populations have similar or lower rates of smoking as other racial and ethnic groups, but they’re more likely to die from tobacco-related causes. Black people have higher rates of exposure to secondhand smoke, including Black children.

Black people are also more likely to smoke menthol-flavored cigarettes. About 90% of all Black smokers use menthol-flavored brands. Advertising for menthol cigarettes targeted Black communities for many years. Menthol cigarettes are harder to quit than nonflavored tobacco. Smoking can raise your risk of blood clots, but obesity may affect this risk for smokers of any race, too.

If you’re Black, you should watch for any one of these early warning signs of a possible DVT, so you can see your doctor for diagnosis and treatment:

  • Leg pain or tenderness, especially when you stand, walk, or climb stairs
  • Swelling around your calf or thigh
  • Skin on your leg that’s warm to the touch
  • Red or discolored patch of skin on the calf or thigh along the muscle
  • Sudden, unexplained cough with bloody mucus
  • Red, swollen, or tender veins that you can see under your skin’s surface
  • Sharp chest pain caused by breathing problems or a blood clot breaking off and moving into your lungs

Avoiding a blood clot before it forms could save your life. Here are some tips to follow to lower your risk of DVT:

  • If you’re on a long trip on a plane or train, or in a car, take breaks to stretch and stand. Long flights can slow blood circulation. Get up and walk once an hour. Change your sitting position. Don’t cross your legs. Wear loose-fitting, comfy clothes when you’re on a long trip. Drink plenty of water and not too much caffeine.
  • Even if you’re just sitting at your desk or on the couch for a long time, pump your feet up and down often. Stand up and do a little dance: make circles with your ankles for 15 seconds.
  • Ask your doctor if you should wear compression stockings or socks.
  • Get regular exercise to improve your blood circulation, keep your lungs working well, and stay at a healthy weight. If you tend to sit still for hours at work or home, take regular walking breaks. Go for a short walk around your home or office building.
  • Don’t smoke tobacco. Cigarette or cigar smoking reduces blood flow and increases your risk of DVT. Ask your doctor for help to quit smoking if you still smoke.
  • Stress can increase your risk of DVT. Modern life is stressful for everyone. Check out some healthy ways to reduce your stress and improve blood circulation, like yoga, meditation, and deep breathing or relaxation exercises.