Chiropractic safety - not far, far worse than we thought

The BCA's plethora of evidence contains two papers addressing the risks associated with chiropractic treatment:

12. Thiel et al. (2007) Safety of chiropractic manipulation of the cervical spine: a prospective national survey. Spine 2007 Oct; 32(21): 2375-8

13. Cassidy et al. (2008) Risk of vertebro-basilar stroke and chiropractic care: results of a population based case control and case crossover study. Spine 2008 Feb 15; 33 (4 suppl): S176-83

Both papers were also cited by Richard Brown (vice-president of the BCA) in his piece in the New Scientist. 

Not wanting to pay to read the full articles, I only have access to the abstracts.

Theil et al. (2007) motivate their study by noting that the risk of a serious adverse event following chiropractic manipulation of the cervical spine is largely unknown, with estimates between 1 in 200,000 and 1 in several million cervical spine manipulations. They looked at the outcome of ~60,000 cervical spine manipulation on ~20,000 patients. No serious adverse events were reported, meaning that at worst, the risk is ~6 per 100,000 manipulation. None of the previous studies had sugested a risk anywhere near this high. This study does not assure us that chiropractic treatment is safe, merely that the risk of a serious adverse event is not much worse than we though. The risk of minor adverse events is rather high.

Cassidy et al. (2008) examine the risk of a rare type of stroke - a vertebrobasilar artery (VBA) stroke - associated with chiropractic visits and primary care physician visits. They paper finds an enhanced risk of a VBA stroke after a vist to either type of practitioner, and attribute this to patients suffering from neck pains or head aches, both known precursors of a VBA stroke, visiting the practitioner. Its not clear from the abstract if this can fully account for the enhanced risk of both types of practitioner. While this study does not demonstrate a greatly enhanced risk from chiropractic treatment, it does so only with regard to one particular adverse event.

A plethora vanishes

BCA have finally done a decent thing and released their plethora of evidence. As predicted, Olafsdottir et al. (2001) is omitted from the list of 27 (now 29) papers. This is by far the best quality trial of the effectiveness of chiropractic treatment of colic available. So why was it omitted? Was it:

1. The BCA are so incompetent that they were unaware of it?
2. The BCA are fully aware of it, but have intentionally ignored it?

While incompetence can not easily be discounted, if they are intentionally ignoring it, that must come close to fulfilling even Judge Eady's surreal definition of "bogus". 

It would also apparently fall foul of the GCC code of conduct's definition of evidence based care, which, as quoted in the BCA's plethora, is "clinical practice that incorporates the best

available evidence from research". Giving chiropractic treatment for colic would thus appear to to breach rule A2.3. 

A secret list of 27 publically available papers

In their extraordinary press release, the litigious British Chiropractic Association claim to have a plethora of evidence that chiropractors can treat various childhood ailments. They asked Simon Singh if he had read 27 papers that, apparently, are so persuasive that "If Dr. Singh had read the research he could not have held the view he expressed in the Guardian unless he simply chose to ignore the facts."

So what are these papers? Obviously the papers are going to be reporting high quality placebo controlled trials with appropriate blinding and randomisation: nothing less is likely to persuade Singh. Chiropractors are real medics (Proof? - they have statutory regulation), so there won't be any customer satisfaction surveys masquerading as evidence. That's the sort of low trick that evidence-deficient homeopaths pull. But as to the identity of the 27, the BCA are rather coy. 

So I, polite as ever, write a short email to the BCA, asking for the list of 27, and promptly receive the reply 

As this case is still sub-judice, I am unable to accede to your request at this time.

So they are hiding behind their lawyers' wigs. Any respectable organisation would have proclaimed their scientific evidence before they launched legal action. 

A quick dredge through ISI web of knowledge revealed that Olafsdottir et al. (2001) is a prime candidate for being accidentally omitted from the list of 27. Her conclusion that "Chiropractic spinal manipulation is no more effective than placebo in the treatment of infantile colic." is not the most convincing evidence in favour of bone crunching.

Solid Evidence?

The ever wonderful homeopathyworkedforme has reached a new low

H:MC21 wishes to express its opposition to the idea that ‘science writers’ have the right to publish articles which attack the livelihood and reputation of medical practitioners without providing solid evidence. 

Naturally, they have no qualms about "medical practitioners" trying to treat either dangerous diseases, or using risky treatments without solid evidence.