Compression stockings can significantly reduce risk for development of deep vein thrombosis during long airline flights, according to a meta-analysis of studies published in Issue 2 (2006) of the Cochrane Database of Systematic Reviews.

Michael Clarke, PhD, and his British research team found in their analysis of trials that compression stockings reduce the risk of symptomless deep vein thrombosis ten-fold, from 10 to 30 cases per 1,000 people to one to three cases per 1,000 passengers.

“It’s an extremely dramatic reduction, but it’s of something that in the first place wasn’t very common. So these stockings reduce a fairly small risk to something tiny,” said Clarke, Director of the United Kingdom Cochrane Centre.

Although travel-associated thrombosis was once called “economy-class syndrome,” the small but real risk of thrombosis is present anytime a person is stationary for many hours, be it on a plane or train, in luxury accommodations or in coach quarters.

There is no definitive link between air travel and increased risks for thrombosis, but some evidence suggests that flights of eight hours or more increase the chances that a person with existing risk factors will develop deep vein thrombosis.

The Cochrane reviewers report results from nine studies that examined effects on travelers who wore compression stockings during flights lasting seven hours or more. Researchers used special equipment to look for symptomless thrombosis among study participants. Some passengers were deemed to have a low-to-medium risk of thrombosis while others were higher-risk travelers.

The review gathered data for more than 2,800 passengers. About half wore some type of compression stockings, whereas the others did not. The researchers’ tests turned up symptomless blood clots in 50 people, three in the compression stockings group and 47 in the no-stockings group.
The reviewers also found that the stocking-footed passengers reported much less discomfort and swelling in their legs compared with travelers who flew without flight stockings.

No one in any of the studies developed a blood clot accompanied by noticeable symptoms, and no one suffered a serious thrombosis-related medical condition.

The reviewed studies did not find any serious safety issues associated with using compression stockings, and Clarke said the risks and costs appear to be moderately low.

“If you put the stockings on and they’re not comfortable, you might take them off,” Clarke said. “And they’ve not cost you a vast amount of money either.”

A pair of compression stockings cost as little as $16 at the drug-store, but higher-quality socks sell for as much as $60. Most people will do fine buying their compression stockings off-the-rack, said Hirsh, who was not involved in the Cochrane review. But people with skinny, long legs or short, thick legs may need to get their stockings custom fitted.