Anna D. Garrett, PharmD, BCPS, CPP
Published Online: Saturday, September 1, 2007

In 2001, the World Health Organization (WHO) began a 2- phase project called the WHO Research Into Global Hazards of Travel (WRIGHT) Project. The objectives of the project were to confirm that the risk of venous thromboembolism (VTE) is increased by air travel and to determine the magnitude of risk, the effect of other factors on the risk, and the effect of preventive measures on risk.

The key findings of the WRIGHT Phase I report include the following:

  1. The risk of VTE roughly doubles with flights greater than 4 hours and increases with longer flights or repeated flights within a short period of time.
  2. Overall, the absolute risk of VTE appears to be about 1 in 6000 healthy individuals, but the risk is primarily concentrated in patients with hypercoagulable conditions, those using birth control pills, or those who have other risk factors such as obesity, extremes of height (less than 5?2? or greater than 6?2?), older age, and cardiovascular disease.
  3. The VTE risk is greatest immediately following a flight, but some risk persists for several weeks afterward.

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