26 October 2016
The occurrence of deep vein thrombosis (DVT) is not limited to economy-class flyers. Photo: Xinhua
The occurrence of deep vein thrombosis (DVT) is not limited to economy-class flyers. Photo: Xinhua

What is economy-class syndrome?

When discussing potential health risks related to taking a long-haul flight in a cramped seat, people inevitably mention the economy-class syndrome.

Most flyers, due to the lack of space in the cabin, stay in their seats for an extended period, and keeping the legs immobile could increase the risk of developing blood clots.

This could result in what is known as deep vein thrombosis (DVT), or the formation of blood clots in a deep vein, mostly in the legs.

If the blood clot breaks off into the bloodstream, it might lead to pulmonary embolism – a blockage in the pulmonary artery, which is life-threatening.

Are plane passengers more likely to suffer DVT if they are flying economy?

In 2001, Dr. Frederic Lapostolle, from the Avicenne Hospital in Bobigny, France, led a large-scale research that involved millions of passengers flying into Paris’ Charles de Gaulle Airport from 1993 to 2000.

The study found positive correlation between long-haul flights and DVT: the longer the flight, the larger the risk for passengers of developing blood clots.

The French researchers looked into the probability of developing lung clots among three types of commuters: those who flew under 5,000 kilometers, between 5,000 and 10,000 km, and 10,000 km or longer.

The results were that 0.01 case was noted in every million passengers flying under 5,000 km, while the number climbed to 1.5 cases in every million passengers flying between 5,000 and 10,000 km, and 4.8 cases in every million passengers flying over 10,000 km.

According to a research report titled Meta-analysis: Travel and Risk for Venous Thromboembolism by Chandra et al. and published in 2009, there is an 18 percent higher risk of clots for each two-hour increase in travel duration using any mode of transport.

That said, the occurrence of DVT is not limited to economy-class flyers.

Whoever keeps their legs immobile for an overly long period of time would put themselves under risks for DVT.

Who are more vulnerable to this illness?

Patients who have been diagnosed with DVT are certainly in the high-risk category.

Those aged 40 or above, those who are tall or obese, pregnant women, or women receiving hormonal contraceptives or hormone replacement involving estrogen would also face a higher risk for DVT after long-haul flights.

Patients who have undergone surgery recently, are suffering from active cancer, or in a certain condition or receiving treatment that cause blood to clot more easily than normal should also stay alert and avoid being immobile during long travelling time.

This article appeared in the Hong Kong Economic Journal on Aug. 23.

Translation by Darlie Yiu

[Chinese version 中文版]

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