WHO Report: Risk for Thromboembolism on Long Plane Rides Is 1 in 6000

The risk for venous thromboembolism approximately doubles after a plane flight lasting at least 4 hours but is still low, about 1 in 6000, according to WHO researchers.


Their report, released online, is based largely on three epidemiologic studies and two pathophysiologic studies.


Among the findings:


• The risk also increases with other forms of travel — such as by car, bus, or train — where riders sit immobile for long periods.


• The risk remains elevated for 2 months after the trip.


• The risk is also increased by obesity, use of oral contraceptives, presence of the factor V Leiden mutation, and extremes of height (above 6.2 or below 5.2 feet).