Skip the Bird's Eye View

If you're a frequent flyer, you may know that long airplane flights increase your risk of deep vein thrombosis (DVT), a potentially deadly blood clot that usually starts in the legs. But did you know that where you sit on an airplane also could affect your risk of developing the condition?

It might, according to a study by Dutch researchers in the British Journal of Haematology. Researchers compared 80 DVT sufferers with 108 control subjects who'd recently flown for at least four hours. They found that passengers sitting in window seats doubled their risk of DVT; no increased risk was found for those in middle seats. Weight appeared to increase the danger: Obese passengers in window seats were six times more likely to develop DVT than those in aisle seats. 

One explanation for the increased risk: Passengers are more cramped in window seats. Another is that passengers fall asleep by a window. In fact, sleeping for several hours at a time during long flights is known to increase one's risk of a blood clot, which can be deadly if it travels from the bloodstream to the lungs, causing pulmonary embolism.

Researchers found that flying business class reduced passenger risk by about 30 percent. They also found that standard advice from clinicians and airlines for preventing in-flight DVT--drinking water, exercising, wearing compression stockings and avoiding alcohol--was inconsequential or had an opposite outcome. 

But one of the study's critics cautioned against reconsidering preventive advice for passengers. The study sample was just too small.