A closer look at link between long flights, blood clots

A long-haul international flight can quadruple or quintuple your risk of developing blood clots in the legs or lungs within two weeks of your arrival, researchers report.

Venous thromboembolism, more commonly called “economy class syndrome,” was linked to air travel in 1954. Since then, no one has pinpointed the magnitude of risk posed by flying.

But Australian researchers had one advantage in estimating the hazards of “economy class syndrome” -- so dubbed because most travelers in economy class are immobilized for hours, without room to exercise their legs. The Australian government has been tracking all international travelers’ arrivals and departures since 1970.

The researchers examined records of more than 5,400 patients admitted to western Australian hospitals with clots in their legs or lungs, and then matched those to international flight arrivals recorded for 1981-99. They found that the critical period for developing the clots was within two weeks of arriving from a long flight. During that interval, 46 Australians and 200 foreigners suffered blood clots; five died.

Over the course of a year, a single long-haul flight increased the risk of developing dangerous clots by 12%, said the study published in Saturday’s issue of the British Medical Journal.

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-- Jane E. Allen