Australia launches DVT investigation

Australia is launching the largest ever investigation into claims that air passengers on long-distance flights run the risk of suffering potentially fatal blood clots.

Deep vein thrombosis (DVT), or "economy class syndrome", is believed to affect passengers forced to sit in cramped conditions for long periods without exercise. Lack of movement can cause blood clots to form in the legs. The inquiry follows the death of Emma Christoffersen, 28, from Newport, south Wales, who collapsed after a 20-hour flight from Australia to Britain last October.

Other passengers who believe they have survived similar blood clots, are suing large airlines and the Australian aviation authorities claiming they should have been warned of the danger. Ms Christoffersen's family says airlines have been aware of the risk for years.

However, scientists are split over whether DVT does pose a threat to air travellers. In October, Dutch scientists assessed nearly 800 patients and concluded there was no link between flying on commercial planes and blood clots in the leg. But a later study in Oslo found that one in 10 patients suffering clots contracted them after air travel. In March, the World Health Organisation and airline representatives warned that a link was possible.

Clots can develop in leg blood vessels when circulation slows down because of lack of exercise. The condition can be fatal if the clots break off and go to the lungs, cutting off the blood flow. Long-haul passengers are advised to avoid alcohol on flights, walk around the aircraft, and exercise in their seats to reduce the risk of clotting. Special supportive stockings are being marketed.

The Australian study, announced yesterday, will examine 10,000 medical and travel records held by Australian government agencies, to see how many long-distance air travellers developed blood clots. John Anderson, the Transport Minister and Deputy Prime Minister, said the study would help determine whether further action was necessary to reduce the risks for travellers.