Air Travel Raises Clot Risks for 2 Weeks
Deep Vein Thrombosis Risk Highest Within 2 Weeks After Long Flight
Nov. 4, 2003 -- A person's risk of developing a potentially
deadly blood clot caused by sitting in an airline seat too long can be four
times higher within two weeks after taking a long international flight.
A new study shows the likelihood of developing deep vein
thrombosis, a condition also known as "economy class syndrome," drops
significantly two weeks after a long-haul flight, which is shorter than the
current two- to four-week post-flight "hazard period" suggested by
Deep vein thrombosis occurs when blood clots develop in the
deep veins of the leg and can happen at any time when the blood can't move
through the vessels properly, such as after sitting in a airline seat for hours
at a time without moving.
These blood clots can travel through the bloodstream and lodge
in the lungs, blocking blood flow and leading to severe organ damage or even
Long Flights Raise Clot Risks
In this study, published in the Nov. 8 issue of the British
Medical Journal, researchers found the risk of death from flight-related
deep vein thrombosis was very small, with about one death reported per 2
million passengers who arrived in Australia on international flights. They say
this risk is small compared with the risk of death from motor vehicle crashes
or injuries at work.
Researchers studied the health records of 5,408 patients who
were admitted to Australian hospitals for deep vein thrombosis and found 46
Australian citizens and 200 foreigners developed the condition within two weeks
after arrival on a long flight.
The study showed that the risk of developing the condition was
four times higher during this two-week period, and 76% of these cases were
attributable to the preceding flight.
Researchers say the fact that more foreigners suffered from the
condition may be the result of longer flight times, which increases the risk of
deep vein thrombosis, and also a so-called "healthy traveler" effect
among the Australians, which suggests that people who travel internationally
often are healthier and less likely to develop deep vein thrombosis than those
who do not travel.
The study also showed that the risk of deep vein thrombosis
rises by 12% each year if a long-haul flight is taken annually.
Advice for People at Risk
But researchers say a person's individual risk of suffering
from a clot might higher if they have certain medical conditions that increase
the risk of clots, such as:
- Varicose veins
- A history of leg clots
- Recent leg or pelvic surgery or a leg injury
In addition, smokers, pregnant women, overweight individuals,
the elderly, and tall people may also have a higher risk of flight-related deep
Researchers say that although the average risk of deep vein
thrombosis is small, airlines and health authorities should continue to advise
passengers on ways they can minimize their risk, including:
- Getting up and walking around the plane during long flights
- Stretching the legs and ankles when seated
- Drinking plenty of water in flight