New evidence proves flight socks reduce DVT risk
Although travel overseas may seem far away at the moment, evidence published today about deep vein thrombosis (DVT) and long haul travel is still newsworthy. This is because deep vein thrombosis can be very difficult to deal with and can cause life-threatening problems. A simple pair of socks has just been proved to reduce some of the most serious risks.
It has long been recognised that air travel might increase the risk of DVT. It has also been thought that wearing compression stockings (“flight socks”) might reduce the risk. Until now, the evidence has not been clear cut.
However, in a Cochrane review (a gold standard source of evidence based health information), the benefits of flight socks have finally been proven.
The problems with DVT
DVTs don’t always have obvious symptoms and can be difficult to diagnose. If untreated, a DVT can cause a pulmonary embolism (PE). This is when part of a blood clot breaks away and lodges in the lungs which can be fatal.
The close relationship between DVTs and PEs is such that the term venous thromboembolism (VTE) is often used to cover both conditions.
VTEs are a leading cause of death and disability in the UK and worldwide. It has been estimated that someone dies from a VTE in the Western World every 37 seconds.
Prolonged travel (along with age, obesity, prior DVTs, current health status, immobility and pregnancy) is recognised as a major risk factor.
“Economy class syndrome”
DVTs have been called “economy class syndrome” and were first associated with flying as a potential cause in the 1950s. Long haul travel also appeared to increase the risks considerably.
Prolonged immobilisation, dehydration, humidity, hereditary factors and lifestyle issues have been suspected as causes for many years.
Do flight socks help?
Because they are similar to those known to be effective in patients recovering from surgery, flight socks are often marketed as being successful in reducing the risk of DVTs. They are widely available to buy, especially in airports.
Flight socks are intended to be worn throughout a flight. By applying a gentle pressure to the ankle in particular, flight socks help blood to flow.
This is because pressure, combined with leg movement, helps blood in surface veins to move to the deep veins and back to the heart. The blood is then less likely to clot in the deep veins and cause a DVT.
However, it has not been clear and certain they had a proven effect, until now.
The Cochrane review included 12 trials with a total of 2918 participants. Almost half of the participants were randomly assigned to wearing flight socks for a flight lasting at least five hours, while the other half did not wear them.
The review has proved that wearing flight socks results in a large reduction in symptomless DVTs among airline passengers. The difference between the two groups is equivalent to a reduction in the risk of getting a DVT from a few tens per thousand passengers to two or three per thousand.
Furthermore, people who wore flight socks also had less swelling in their legs. Fewer passengers developed superficial vein thrombosis. There did not appear to be any problems or risks associated with wearing the socks.
Because DVTs do not always have any symptoms, passengers were carefully assessed after the flight. This helped to detect any problems with the circulation of blood in their legs, even if they had not noticed any problems themselves.
None of the passengers developed a DVT with obvious symptoms (slowly developing leg pain, swelling and increased temperature) and no serious events or deaths were reported.
It is not currently possible to say that wearing flight socks definitely reduces the risk of death from DVT (or PE or DVTs with symptoms), because it didn’t happen to anyone in either of the groups in the trials. To prove the link with reducing mortality would require very large, randomised trials.
It is clear, however, that wearing flight socks results in a substantial reduction in the incidence of symptomless DVT.
When long haul travel becomes more frequent again in the future, for leisure or business, it is well worth wearing flight socks, particularly if you have known risk factors.
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