Travelers' clots more common in overweight people or those on the pill

Monday, December 8th 2003, 12:00 am

By: News On 6

CHICAGO (AP) _ New research suggests the risk of potentially deadly blood clots from long airline flights is small but rises sharply in people who are older, overweight or taking birth control pills.

In one study, blood clots in the lung _ the most serious travel-related kind _ occurred more frequently on flights lasting longer than eight hours.

In that study, 16 cases were detected among international passengers arriving at Spain's Madrid-Barajas Airport from 1995 to 2000. All of them involved flights longer than six hours.

The overall lung blood-clot risk was 0.39 cases per 1 million passengers, compared with 1.65 per million passengers on flights longer than eight hours, researchers said.

``The low incidence ... does not justify social alarm,'' said the researchers, led by Dr. Esteban Perez-Rodriguez of Madrid's Ramon y Cajal Hospital.

The study was published with two smaller ones on clots and air travel in Monday's issue of Archives of Internal Medicine.

The clot problem, sometimes called ``economy-class syndrome,'' appears to stem from prolonged sitting in cramped quarters without getting up and walking around. Clots that form in the legs can travel to the lungs and cause sudden death.

Another study involved 210 patients with limb and lung blood clots and 210 healthy people. Clots were twice as common in patients who had recently traveled and significantly higher in patients already at risk, including women taking birth control pills, who were 14 times more likely to develop blood clots than non-travelers not on the pill, Dr. Ida Martinelli and colleagues at the University of Milan reported.

In the third study, German researchers found varicose veins and being overweight were common among travelers with blood clots. Advanced age is also a risk factor; the average age of travelers with clots was 66.