Compression stockings help prevent deep vein thrombosis

People wearing compression stockings on long-haul flights may have one tenth the risk of developing a deep vein thrombosis (DVT) compared to those who do not wear compression stockings. So concludes a systematic review of medical research to be published in The Cochrane Library.

"This review shows that airline passengers travelling for long distances can expect a substantial reduction in the incidence of symptomless DVT if they wear compression stockings," says lead Review Author Prof Mike Clarke, Director of the UK Cochrane Centre, Oxford.

DVTs are blood clots that partially or totally block veins running deep inside the body, usually in the legs. They have been of concern for years in patients lying in hospital beds, and more recently in passengers on aircraft. These people share a number of common features: both sets tend to become dehydrated and breathe air that has a low humidity, and both groups do not move about very much.

To counteract this lack of movement, patients in hospitals are often encouraged to wear stockings that apply pressure to the lower leg. The gentle pressure helps maintain blood flow and reduces the number of blockages. As people have become more aware of the risks of developing a DVT while flying, researchers have started to assess the potential benefit of compression stockings in airline passengers.

Performing a systematic review, the Review Authors based in Oxford and Copenhagen searched for high quality studies in which people had been randomly assigned to either wear or not wear stockings, before flights that would last at least seven hours. "We found nine such trials involving over 2,800 people of different ages, sexes and risk categories, who were split almost equally between the groups" said Monica Kjeldstrxm from the Nordic Cochrane Centre in Denmark.

Of the 2,637 people with follow-up data, a total of 47 people who were not wearing stockings developed DVTs, compared with only 3 of the stocking-wearing group. Review Author Dr Sally Hopewell, another of the researchers, said "the DVTs in these studies were detected by a clinical examination after the flight and none of the DVTs caused symptoms that the person was aware of or led to other health problems."