Doctors Unite in their Fight Against Economy Class Syndrome

Vienna , 8 June 2007 – The case of a young English woman who died shortly after a long haul flight from Australia in 2000 has gradually faded from public consciousness. That is unfortunate. Her death highlighted a problem that has long been grossly neglected: the risk to air travelers of venous thrombosis. A contributing factor to the cramped seating in economy class flights may be specific to the cabin environment, i.e. the low air pressure.

With two billion people boarding a plane annually, the danger venous thrombosis presents should be taken very seriously, says Professor Frits R. Rosendaal, from the Leiden University Medical Center (NL), at the European Hematology Association Congress meeting in Vienna from 7 to 10 June 2007.A recent WHO project (the WRIGHT, or WHO Research Into Global Hazards of Travel, project), the results of which are about to be made public, has shown that air travel is associated with a two- to threefold increased risk of developing blood clots in the legs, (deep vein thrombosis or DVT) or in the lungs (pulmonary embolism or PE).

“The risks of developing thrombosis when traveling are higher for people with certain common abnormalities in the blood, for women who use birth control pills, or people who use sleeping pills on a flight, as well as for people who are very tall, very short, or overweight”, Professor Rosendaal says. “There may be a 50 to 100-fold increase in risk for people with combinations of those factors.”

5 to 10 % of thrombosis sufferers die as a result of the blood clot

Of course people may suffer thrombosis without ever having flown on a plane. Venous thrombosis (DVT and PE) is a common disease, affecting between one and three people per thousand. PE alone kills more people in the industrialized world than AIDS, breast cancer and traffic accidents combined. Between 5 and 10% of thrombosis sufferers will die as the result of the blood clot. “But the degree to which air travel has contributed to the incidence of thrombosis is only now receiving adequate attention”, Professor Rosendaal underlines. “This isextraordinary, considering the first cases of thrombosis in air travelers were reported as long ago as 1954.”

Researchers into air travel related thrombosis have focused particularly on two aspects, investigating whether prolonged immobility in a confined space is a contributing factor, and whether specific aspects of the cabin environment such as low air pressure may aggravate the condition.

Risk may increase 100 fold with overweight or oral contraceptives

The WRIGHT project included a study of nearly 2,000 patients with thrombosis and a survey of 9,000 frequent travelers. Among its conclusions, says Professor Rosendaal, is that in the eight weeks after a flight of more than four hours, the risk of thrombosis is increased two- to threefold. Overall, one in 4500 travelers develops thrombosis. For those individuals with a combination of common risk factors, such as oral contraceptive use and excess weight, the risk of developing blood clots after air travel may increase 100 fold. Professor Rosendaal: “Studies which included an experimental flight with volunteers showed clearly that immobility of passengers on long flights is the main cause of blood clots, but that cabin conditions such as low air pressure may also contribute.”

For most people, however, the absolute risk of thrombosis is quite low, and so preventive measures need to be carefully evaluated to ensure any side effects don’t outweigh the advantages of reducing thrombosis risk, says Professor Rosendaal: “This is particularly relevant to the use of anti-thrombotic drugs such as oral anticoagulants, heparin and aspirin. Use of such drugs is perhaps indicated for travelers with the highest risk of developing blood clots.” Beyond medications, researchers are interested in the possible benefits toair travelers of wearing elastic stockings or using mechanical compression devices which can be strapped to the leg and which exert a gentle pressure once every minute.

Increased seating space may help

There are some things ordinary travelers can do to protect themselves from developing blood clots. “Use of sleeping pills on long haul flights should be avoided”, says Professor Rosendaal, “simply because people barely move while they sleep. Excess alcohol is also likely to make people less mobile. And passengers can undertake some exercise.” The experts call in airlines to adapt to growing awareness of the risk of thrombosis among travelers: “Increased seating space would help, and special seats for the very tall, the overweight and the very short should be available.”But at present there is no firm data on the efficacy and safety of methods to prevent travelers’ thrombosis.

The next step must then be to establish best practice in thrombosis prevention for the numerous people who fly each year says Professor Rosendaal. Research centers around the world have already agreed to conduct WRIGHT 2, which will perform randomized trials among high and intermediate risk travelers. These studies will take four years and cost 4 million euros, and doctors involved in the project are urging the EU and national governments to help make air travel safer by supporting research into travelers’ thrombosis.

Contact:

B&K Medien- und Kommunikationsberatung GmbH
Dr. Birgit Kofler; Daniela Pedross, MA.
Porzellangasse 35/Top 3, A-1090 Vienna
Phone: 0043-(0)676-6368930; Fax: 0043-(0)1-319-43-78-20
E-Mail: kofler@bkkommunikation.at; pedross@bkkommunikation.at

About EHA

The European Hematology Association (EHA) aims to promote excellence in clinical practice, research and education in European hematology.

Today, EHA – with over 2600 active members from 95 countries – is a consolidated organization that pursues a large and growing number of projects and programs. An Executive Board and Councilors elected by the membership form the governmental body responsible for the strategy and organization of the association.

About the EHA Annual Congress

The EHA annual congress is organized every June in a major European city. Over the years the congress has become the meeting place for hematologists in all fields of the speciality. The congress program has sessions on clinical and laboratory hematology and covers all the major hematological subspecialties, including hemato-oncology, red cell disorders, hemostasis, thrombosis, pediatric hematology and transfusion medicine.