The Great DVT Conspiracy?
BBC's Panorama has claimed that airlines refused to assist research into the relationship between deep-vein thrombosis and flying. An old cover-up - or a new panic?
A BBC1 Panorama programme at the beginning of June 2001 apparently exposed airlines for refusing to assist research into deep-vein thrombosis (DVT). But how much light does this shed on the relationship between DVT and flying?
Panorama gave an airing to an assortment of cover-up theories. DVT survivor Terry Salsbury claimed: ‘I’m sure that airlines do know about it, and it’s vital that more research is carried out into the risks.’ Farrol Khan of the Aviation Health Institute said that airlines ‘don’t want the problem to come out into the open’ (1).
It is alleged that airlines knew about possible links between flying and DVT up to 10 years ago. Yet as the evidence stands today, there is no conclusive link between DVT and flying; and with or without pressure from Panorama, airlines today seem to be willing to support research.
In March 2001 airlines agreed to a major research programme surveying hundreds of thousands of passengers before and after they get on planes (2). Given the fact that evidence at present suggests, at most, that the link between DVT and flying is very small, and mainly affects those already at risk from DVT (3), the money and time to be devoted to this major research project look pretty generous.
Other witnesses called upon in the Panorama programme included five scientists said that their requests for information from airlines had been refused or ignored. When Professor Sam Shuster asked British Airways (BA) for access to passengers for research in 1996, he was refused on the grounds that ‘most passengers do not wish to get involved and are simply keen to get on with their journey’. This does not seem so unreasonable – who wants their holiday to the Caribbean to turn into months of form-filling and blood tests?
A BA spokeswoman added that the airline gets hundreds of such requests every year, and cannot cooperate with all of them. (Airlines do have other important things to worry about, like organising the safe takeoff and landing of thousands of planes every day.)
Interestingly, two articles covering the Panorama programme mentioned that ‘up to one in 10’ long-haul passengers could be affected by DVT (4). This figure was derived from a recent study published in The Lancet medical journal, which found a risk of DVT 40 times that found in previous studies. A commentary in the same journal presented persuasive evidence that the result was best explained by fundamental errors in the study method (5).
Dr John Cruickshank, who complained to Panorama that his offer to make a safety video for airlines had been turned down, said ‘Okay, it’s not pukka science but we have to address the issue’.
Actually, the DVT saga would greatly benefit from a bit more pukka science, and more vigorous attempts to address the issue.
Spot the clot – smell the rat, by Josie Appleton
Are you the one in four?, by Josie Appleton
Cars, trains and blood clots, by Josie Appleton
(1) BBC News Online, 11 June 2001
(2) BBC News Online, 13 March 2001
(3) See Are you the one in four? and Cars, trains and blood clots, by Josie Appleton
(4) Guardian, 11 June 2001
and BBC News Online, 11 June 2001
(5) See Spot the clot – smell the rat, by Josie Appleton
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