A recent study in The Netherlands showed that regular airline passengers are more than three times more likely to develop life-threatening blood clots than occasional fliers. But the findings are no reason to cash in those air tickets, as it also showed that the overall risk is relatively low – one incident for every 4,656 long-haul flights.
The study examined the incidence of blood clots among almost 8,800 employees of international organizations, matching the data with risk factors and travel records for flights between January 2000 and December 2005.
People who took five or more flights during the study period were almost three times more likely to develop a blood clot than those who took one or two flights, according to Dr Frits Rosendaal of the department of Clinical Epidemiology and Haematology at Leiden University Medical Centre. The study was published in September by the Public Library of Science (PloS) and reported by Australia’s Sydney Morning Herald and Britain’s Daily Mail newspapers. Travelers under 30, women using oral contraceptives and passengers who were particularly tall, short or overweight were also more likely to develop blood clots. He explained that limited leg space made very tall people more susceptible, while very short passengers were often unable to reach the floor, putting increased pressure on their legs.
Research has linked flying to deep vein thrombosis – a.k.a. “economy-class syndrome” – for over 50 years. According to a March 2007 article in The Ergonomics Report™, a publication for readers with a professional interest in ergonomics and human factors, in-flight hazards are as tricky to untangle as risk factors for other ergonomics-related conditions, such as musculoskeletal disorders. Prior medical history, medication, obesity, stress, the sardine-like conditions on board and climate conditions in the cabin come into play, but there is scant agreement on the level of risk attached to each and if they interact.
The Dutch study is the first to calculate the overall risk of thrombosis after air travel. It promises to weigh in to a debate that stretches back for decades.
Sources: Public Library of Science; Sydney Morning Herald; Daily Mail; The Ergonomics Report™