Those who travel and spend many hours in airplanes are at a triple risk of developing venous thromboembolism (VTE) in the legs, a rare but potentially deadly clot-forming condition, researchers at Harvard University in Boston have reported.

A venous thromboembolism is more likely to happen in overweight people, during pregnancy or after taking the contraceptive pill. The condition also occurs if a person is not able to walk about because of illness or injury. VTE can be fatal if the blood clot breaks up and travels through the vein to the lungs. The clotting is also known as deep vein thrombosis. Symptoms of the condition include swelling, pain and redness in the leg, or legs.

There has already been lots of research looking at whether long-distance travel, and in particular air travel, increases the incidence of a blood clot forming. Up to this time, the results have not been conclusive. The team of experts, led by Dr. Divay Chandra, carried out their own investigation in order to see if they can draw any conclusions. The new findings are based on the analysis of the pevious 14 studies which involved up to 4,000 patients that met their criteria.

The Harvard investigators said that if all the given information from the past studies is pulled out, it turns out that travel doubles the risk of developing blood clots. They said that the studies that did not demonstrate a higher incidence, had problems that made them not reliable, and that if the figures are taken out from these less reliable studies, travel almost triples the risk of developing blood clots.

The results of the investigation revealed that there is an 18 per cent higher risk for every 2 extra hours of travel by any mode, and a 26 per cent higher incidence for every two hours of travel by airplane. The people who are most at risk are those taking estrogen, extremely obese, individuals with thrombophilia, and those with a chronic condition, the experts said.

Researchers explained that blood clots are extremely dangerous, and not only because they are associated with strokes and heart attacks, but also because they do not necessarily remain in the position they were formed in. In other words, like it was mentioned above, during the trip, a clot could move up to the lungs, and kill a traveler very fast, without any chance of getting to a hospital in time.

The scientists say that taking anti-clotting drugs is not needed while traveling, especially for those who have a good overall health. However, for individuals who are already at risk of developing such conditions, even without traveling, taking such medications before going on long trips, either by car, or by airplane, could be necessary. In any case, people who are aware that they are predisposed to this condition, but have to take trips, should, at least every 2-3 hours, get out of their seats and walk around for several minutes in order to get the blood circulate and pump back in the limbs, and to prevent the formation of blood, the experts added.

Researchers say that the best thing to do while on the plane is to drink water, one glass every two hours, and flex calf muscles against the foot rest if there is no possibility to get up and walk around. Coffee or alcohol are not recomended, because they dehydrate you. "Liquids dilute blood, which makes it less likely to clot, and mobility keeps the blood moving through the lower extremities," researchers wrote. "Staying hydrated and making sure you move are not proven measures to prevent VTE but they can help." The experts added that more studies are needed on preventive measures.

In the conclusion researchers wrote that their findings demonstrate for the first time that there is a clear relationship between travel and venous thromboembolism. Worldwide, 2.5 billion passengers will be traveling by air just in 2010, which underscores the large global population at risk for this serious condition.

The study is published in the July issue of the journal Annals of Internal Medicine.

Tags: Heart Disease, Travel

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