The risk of developing deep vein thrombosis during a flight is often overestimated

July 23, 2009

The risk of developing deep vein thrombosis during a long flight is often overestimated. According to the German Institute for Quality and Efficiency in Health Care (IQWiG), this condition is very unlikely in healthy travellers.

When people wear a cast or splint after a sports accident, on the other hand, many are not aware that they have an increased risk of deep vein thrombosis in their leg and pelvic area. This is emphasised in information published today on IQWiG's website Informed Health Online.

Blood clots can travel to lungs, leading to pulmonary embolism

If you are unable to move your legs regularly, blood flow through your veins is slower than usual. As a result, blood may clump together, forming a blood clot which can lead to deep vein thrombosis. "This can become dangerous if the blood clot dislodges, travels to the lungs and blocks a blood vessel there," says the Institute's Director, Professor Peter Sawicki. "This complication, called a pulmonary embolism, can reduce the supply of oxygen to the body's cells, overstrain the heart and even cause heart failure."

Even in higher-risk groups the risk of air-travel-related thrombosis is still well below half a percent

During the travel season we often hear that long-haul flights increase the risk of deep vein thrombosis (sometimes called "economy class syndrome"). The Institute summarised the results of research on deep vein thrombosis and air travel, involving the experiences of millions of air travellers. They found that only about 2 to 5 out of every 10,000 people who took a flight longer than 6 to 8 hours developed deep vein thrombosis that caused symptoms (at the most 0.05%). Even people who had a higher risk - for example, because they had large varicose veins or were very overweight - were not highly likely to develop deep vein thrombosis: only 20 out of every 10,000 travellers were affected (0.2%). The Institute did not find any convincing evidence that people who flew for less than 4 to 6 hours had an increased risk of thrombosis.

"By the way," says Professor Sawicki, "if you want to lower your risk by wearing compression stockings, you should put them on at least 2 hours before the flight and keep them on throughout the entire journey. Research has shown that these stockings lower the risk of deep vein thrombosis somewhat when used in this way."

Wearing a cast or splint increases the risk of deep vein thrombosis

If people have to wear a cast or splint, for example after fracturing a bone or tearing a ligament, they can only move their leg a little bit, if at all. Many people do not know that this also increases the risk of developing a blood clot in a vein in their leg or pelvis. "To prevent serious complications, it is important to get back on your feet and move around again as soon as possible," stresses Professor Sawicki. "If that is not possible, for example because putting strain on the leg too soon could slow down recovery, there are effective medications that can be used." These so-called "anticoagulant" medications reduce the blood's ability to clot. Heparins are among the most established anticoagulant medications. They are injected subcutaneously (under the skin).

More information: http://www.informedhealthonline.org

Source: Institute for Quality and Efficiency in Health Care