Researchers analysed the results of nine comparative trials carried out in the UK and Italy on nearly 2,500 flyers over a two-year period.
Each study contained a group wearing knee-length graduated compression stockings and a control group who did not wear the stockings.
They discovered that only two of the 1,237 participants wearing the stockings developed DVT compared with 46 of the 1,245 people in the control groups.
Having carried out a detailed weighted analysis of the results and the factors examined in each of the nine studies, the authors concluded that a passenger not wearing graduated compressions stockings was 12.5 times more likely to develop DVT.
All the participants who took part in the studies were also advised to walk or exercise regularly, drink water, avoid salty food and make sure that bulky baggage didn't restrict their leg movement.
"The risk of venous thrombosis was first recognised in 1940 when 21 people died from pulmonary embolisms after prolonged sitting in air raid shelters in London" points out co-author Professor Hsiu-Fang Hsieh from Fooyin University in Taiwan.
"However, it wasn't until 1954 that researchers first suggested the link between long-haul air travel and DVT. Since then it has become more common for people to travel long distances by air and concern about the risks of DVT have increased."
Graduate compression stockings may be a relatively new concept for air travellers, but they have been around for thousands of years, according to Professor Hsieh.
"There is evidence that the ancient Egyptians recognised the benefit of leggings that applied greater pressure at the ankle than at the knee" she says.
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Contact: Annette Whibley
wordwizard@clara.co.uk
Blackwell Publishing Ltd.
13-Jun-2005