Researchers at Harvard University in Boston have found that those who travel are three times more likely than those who do not to develop venous thromboembolism (VTE), the development of a blood clot in a vein, usually in the legs. The condition is also known as Deep Vein Thrombosis.
"Our findings demonstrate for the first time a clear association between travel and VTE," the researchers said in their report, published in the Annals of Internal Medicine.
VTE can be fatal if the blood clot travels to the lungs. Symptoms of the condition include swelling, pain and redness in the leg, or legs.
The research group, headed by Dr. Divay Chandra, compiled previous research found in 14 studies involving some 4,000 patients that met their criteria.
The threat of developing VTE is not limited to air travel. The researchers also show a measurable increase in the condition for every two hours sitting in a car. The research shows the longer the trip, the greater the threat of VTE.
The study suggests the situation is serious enough for more research to be carried out into how to keep travelers healthy, but not serious enough to justify giving airline passengers anti-clotting drugs.
"Worldwide, 2.5 billion people will travel by air alone in 2010, which underscores the large global population at risk for this serious condition," the researchers wrote. They said drinking extra fluids and getting up and moving every two hours or so is worthwhile.