Travellers' clot risk 'tiny for many'

Some passengers are at much higher risk

Only a small minority of long-haul passengers should be worried about the risks of deep vein thrombosis (DVT), suggests a study.

An analysis of DVT patients at one London hospital suggests that unless you have just had an operation, are taking hormone replacement therapy (HRT), have cancer, or have already had a clot, there is little to fear.

The study comes as new class of drug designed to reduce the risk of blood clots was launched in the UK.

Public fears have grown about the dangers of clots forming in the lower legs during long-distance travel.

Lung clot

The condition was dubbed "economy class syndrome", but the problem can arise in patients immobile for long periods during any form of long-distance travel.

The clots can lodge painfully in blood vessels in the legs, and, in some cases, travel to the lung, and cause a far more dangerous condition called pulmonary embolism.

The study, by doctors at King's College Hospital in London, looked at 568 patients who attended a DVT clinic, and looked at the circumstances in which the clot happened.

No link

They found that there was no statistically significant link between travel and DVT, including long-haul air travel, in patients who were in good health.

For people without these risk factors, long-distance travel is really nothing to worry about

Dr Ander Cohen, King's College Hospital

However, among those who had "additional risk factors", such as a previous clot, HRT use, or cancer, long-haul travel did increase the risk of having a clot threefold.

Having an operation - such as a hip or knee replacement - was the most significant risk factor.

People in this group were more than six times more likely to suffer a clot without even stepping on a plane.

Dr Ander Cohen, one of the study authors, told BBC News Online: "If a patient who had just had an operation came to me and asked me about taking a flight, I would tell them to hold back.

"However, for people without these risk factors, long-distance travel is really nothing to worry about."

He said that aspirin, which is given to some patients at risk of clots to prevent the problem, was not effective enough to be recommended.

The newly-launched drug, Arixtra, is particularly aimed at patients undergoing major orthopaedic surgery of the lower limbs - such as hip and knee replacements.

Studies suggest it could be more effective at preventing clots than a currently-used drug, low molecular weight heparin.

More than 180,000 people a year in the UK undergo surgery of this type - one in 20 will develop a blood clot that requires medical attention.

However, many more will get a "silent" clot, which could cause unseen damage and make subsequent, more dangerous clots more likely.