Friday, 24 July 2009

Science, skepticism, and chiropractors

In an apparent response to the great indignation stirred up by their libel suit against Simon Singh (which I have blogged about already, here and here), the British Chiropractic Association has put forth another defense of their actions (and their profession). This time, it takes the form of a letter to the British Medical Journal written by BCA vice-president Richard Brown. It is freely available on the BMJ's website, alongside a thorough critique by Edzard Ernst (professor of complementary medicine in Exeter) and an editorial by Fiona Godlee of the BMJ.

Brown claims that the BCA didn't want to sue Singh, but he left them no choice when he refused to retract his original article. That's the one that claimed the BCA promoted chiropractic as a treatment for childhood conditions when there is no good evidence that it is effective. He lists several studies, claiming that they demonstrate the effectiveness of chiropractic for "various childhood conditions." In effect, his letter suggests that they have evidence to support their medical claims, but that it is appropriate to sue someone who criticizes those claims (rather than simply presenting the evidence, as they were invited to back when Singh's article first came out).

Ernst doesn't address the legal or political issues at all, instead producing a thorough and easy-to-follow demolition of the studies that Brown puts forth - each of which is either irrelevant to the claims being debated or is of insufficient quality to count as substantial evidence. He also points out that "At least three relevant randomised controlled trials and two systematic reviews are missing from [Brown's list]." That is, not only is the BCA's evidence base of poor quality - they rely on it while ignoring good evidence that the interventions don't work.

Godlee's editorial provides a good summary. Remember that this is comment from an editor of one of the most prestigious medical journals around. It's titled "Keep libel laws out of science." (Sound familiar?) It is a masterful piece of writing, so you ought to read the whole thing. But here are some of the more delightful bits:
I hope all readers of the BMJ are signed up to organised scepticism. It’s not a blog, but it could be. It’s one of the four principles of good science as articulated by Robert Merton nearly 70 years ago.
The Guardian offered the BCA an opportunity to lay out their evidence rather than to sue him for libel. The BCA opted to sue.
Readers can decide for themselves whether or not they are convinced [by the evidence presented by Brown]. Edzard Ernst is not. His demolition of the 18 references is, to my mind, complete.
Weak science sheltered from criticism by officious laws means bad medicine.
And naturally, she echoes another medical journal editor who was faced with similar bullying recently:
And last year when chiropractors threatened to sue over an article in the New Zealand Medical Journal, its editor Frank Frizelle spoke for all of us when he asked them to provide "your evidence not your legal muscle."
As Chris Kavanagh points out in his post on this (where I learned about this latest development), the BCA has yet again failed to vindicate themselves in any way. They have at last presented their evidence in a forum where its actual quality matters, rather than its superficial plausibility. Which is good - they should have done this in the first place, rather than stooping to the level of legal bullying. But the fact is that their evidence is poor. Very poor. The fact is that Simon Singh was right in his original article. This was bound to come out when the issue made it to a scientific journal.

I don't know if this will have any effect on Simon's case - after all, that is based on a fundamentally bad law, and does not (as far as I know) depend on the quality of the scientific evidence. But perhaps it will help people see through the veneer of medical respectability that chiropractors try to project.

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