US Pharm. 32(11)77-78.

A survey of nearly 9,000 business travelers found that long flights tripled the risk of developing venous thrombosis. According to Suzanne C. Cannegieter, MD, PhD, of Leiden University, The Netherlands, and colleagues, the risk of developing symptomatic clots for healthy individuals is low after a flight of four or more hours, but increases with more and longer flights.

The researchers noted that while the study only investigated healthy individuals with an average age of 40 and without previous deep-vein thromboses or pulmonary emboli, the absolute risk might be greater in the general traveling population. The risk also increased with exposure to more flights within a short time frame and with increasing duration of flights. The risk was particularly high for travelers younger than 30, for women (especially among those taking oral contraceptives), and for individuals who were particularly short, tall, or had a body mass index above 25 kg/m2.

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