clotting factor: the hidden danger of flying
by Russ Kick (russ@mindpollen.com) - July 03, 2001
They kill an estimated 30,000 airplane passengers per year, but the US airlines won't tell you about them, and the media are keeping their mouths shut. Blood clots formed during flights are the most common hazard of air travel.
Cramped seating in airplanes has given hack comedians a lot of material, but it's also given something to tens of thousands of passengers--deadly blood clots. Britain and Australia are abuzz over "economy class syndrome," as it's being called, but the US media have spoken nary a whisper about it. They're perfectly willing to give the airlines a hard time over delayed flights, lost luggage, lousy customer service, and other inconveniences, but when it comes to a serious threat to our health, the watchdogs are asleep.
Deep Vein Thrombosis
Deep Vein Thrombosis (DVT) is the condition in which a blood clot forms in a vein--usually one deep in the leg. Like all clots, the ones formed from DVT present a major health risk, since they block blood flow and can easily detach. Clots from legs can get carried to the lungs or heart, causing severe medical problems, not the least of which is death.
DVT can be caused by an injury, surgery, radiation therapy, or prolonged inactivity, such as sitting still in airplanes, theaters, and even at desks. Elderly people, overweight people, cancer patients, and pregnant women are at special risk, but thrombosis can and does occur in people of all ages, genders, and levels of health. In fact, three members of the British Olympic team--who were obviously in prime physical condition--had to be treated for DVT upon arrival in Australia for the 2000 Summer Games.
"Economy Class Syndrome"
Long flights are a natural breeding ground for blood clots, since airplanes aren't exactly roomy, and most passengers don't move much during flight. Because coach class is most like a sardine can, DVT formation during flights has become known as "economy class syndrome." This is actually a misnomer since DVT often strikes people in first class and even captains in the cockpit.
Naturally, the longer the flight, the more risk is involved. Doctors have reported cases of DVT that developed during flights as short as three hours. International flights are especially dangerous, because they can last 20 or more hours.
Non-fatal cases of flight-related DVT that have made headlines involve a Qantas flight attendant, a Sydney doctor, an Australian Member of Parliament, a CEO of one of Britain's largest ad agencies, and even former Vice President Dan Quayle.
The most well-known fatality is Emma Christofferson, a 28-year-old "fitness fanatic" who collapsed right after getting off her Sydney to London flight. Her death in October 2000 kick-started the concern over flight-related DVT.
The Studies
There is little doubt that cramped conditions can trigger DVT. One Lancet study showed that 10 percent of air travelers over 50 may develop a clot during flights of more than eight hours. Another report, by a British vascular surgeon, "shows that 13% of DVT cases in a sample study occurred in patients who had travelled on long journeys, mostly in aircraft," according to the Sunday Times of London. The Washington Post notes, "In one study, people treated at the hospital for blood clots were four times more likely to have recently gone on a long trip than those treated at the hospital for other medical problems."
Researchers in Honolulu discovered that 20 percent of people treated for clots had developed DVT during a flight, and a study in Aviation, Space & Environmental Medicine journal found that 50 percent of a group of clotted patients had flow recently. Other studies have found that six and five percent of people who developed clots got them because of flying.
Some naysayers point to a recent study of 788 people published in The Lancet that failed to find a statistically significant correlation between flying and blood clots. However, out of 60 studies and articles in medical journals, these researchers were the only ones who said that travel was not a risk factor.
Frequency
Flight-related DVT is not being studied systematically, so it's difficult to tell how many people have been affected by it. According to The Age of Melbourne, Australia, some studies report that every year 30,000 people die from flight-related DVT around the world.
At the beginning of this year, Ashford Hospital in Surrey released a report estimating that at least 2,000 people die of flight-related DVT each year in Britain alone. In fact, DVT kills at least one person per month at London's Heathrow airport.
The Aviation Health Institute estimates that every year in the UK 30,000 people develop DVT--mostly non-fatal cases--because of flights.
In December 2000, a doctor at the Nippon Medical School clinic at Tokyo's Narita Airport said that 25 people--including an American pilot?have died from DVT at the airport in the past eight years. In addition, 100 to 150 people are treated for the condition every year at the airport.
The actual number of people who developed flight-related DVT is likely to be much higher, especially if the clot doesn?t result in death. Many articles on the subject quote medical authorities who note that clots may not make themselves known till days, weeks, or longer after a flight. Plus, even if the person sees a doctor, the connection to air travel may not be uncovered.
The US government doesn't keep statistics and no nationwide studies have been done, but the Airhealth.org Web site has extrapolated some figures.
We do know that each year 800,000 people are hospitalized with blood clots, and an additional 70,000 die. If we take the lowest rate of flight-related DVT found in the studies--5 percent of clot patients (mentioned above)--that still equals 40,000 people hospitalized and 3,500 dead each year in the US due to blood clots formed on airplanes.
Remember, that's a conservative estimate.
Slow, Dodgy Responses
The responses of airlines to this danger has been sluggish at best, and conniving at worst. Despite being warned about flight-related DVT over 30 years ago, airlines outside the US are just now doing something about it, and US airlines are doing nothing. Two doctors wrote a scientific paper on the condition in 1968, and the leading British medical journal The Lancet published a letter from a group of concerned doctors in 1985.
Yet the industry ignored scientific evidence and released "misleading statistics," according to The Observer of London. The paper says, "Our investigation has uncovered a culture of deceit at some airlines which has been allowed to thrive due to complacency at the Department of Health and the Civil Aviation Authority."
The Observer also points out that "airline company doctors have known about the risks of immobility since 1940 and the risks of immobility on long-haul flights since 1968"; "British Airways has not allowed doctors access to its passengers to do more research"; and "British Airways highlights a misleading study on its website which downplays the risks of long flights."
Seriously though, after waiting to see the man for 3 hours, the Doc says it's not a blood clot - he doesn't know what the deal is?! PHEW!! (I guess) 
Facebook
Twitter