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Why do unscientific claims by some chiropractors not appear to put patients off?

Marc Wilson is a psychology professor.

Photo/Getty Images
Photo/Getty Images

It hasn’t been the best of months for chiropractors. Australian practitioner Ian Rossborough has had more than his 15 minutes of fame thanks to an instructional video showing him adjusting the spine of a four-day-old baby.

From what I’ve seen, there is limited evidence that chiropractic is beneficial for infants. The most recent case study review, published in 2015, notes a range of adverse events associated with manipulation of children. And although it also says these are rare, as with conventional medicine any mistake is one too many.

In April, the New Zealand Medical Journal ­published a research letter by Mark Hanna and Mark Honeychurch reporting that more than half of the 137 New Zealand chiropractors’ websites they examined made therapeutic claims that can’t be substantiated – the sorts of claims that have previously been the subject of complaints to our Advertising Standards Authority. The list includes benefits for colic, ear infections, allergies, ADHD and ­enuresis (bed-wetting).

Simon Singh: asserted chiropractic was “bogus”. Photo/Richard Cooper
Simon Singh: asserted chiropractic was “bogus”. Photo/Richard Cooper

In their opinion, 35% of the websites they looked at contravened the Chiro­practic Board’s guidelines by using testimonials to promote their services. And the 1981 Medicines Act, as it happens. The NZ Chiropractors’ Association responded by stating that Hanna and Honeychurch’s note is already out of date following a review and new set of guidelines.

I’ve also been looking at how chiropractic websites describe their services to see if the claims have changed. I started partly because of a 2009 defamation case brought by the British Chiropractic Association against science writer Simon Singh for describing chiropractic as “bogus”. The courts eventually ruled in 2010 that Singh’s claim was his honest ­opinion and he won his legal appeal. But not before the research evidence for chiropractic as a treatment for asthma and other complaints was put forward to be weighed, and in my opinion that evidence was rather light.

During the case, the chair of the ­McTimoney Chiropractic Association (MCA) emailed UK chiropractors and instructed their members to remove any unsupportable therapeutic claims. It also advised, “If you use business cards or other stationery using the ‘doctor’ title and it does not clearly state that you are a doctor of chiropractic or that you are not a registered medical practitioner, stop using them immediately.” Many complied.

I’ve found that many chiropractic websites in New Zealand appear to play word games to get around restrictions on making health claims. This commonly takes the form of statements such as “We do not treat [X condition], but because [X] is a nervous system ­disturbance, and chiropractic attempts to reduce nervous system disturbance, many parents have found chiro­practic care helpful.” Why not go the whole hog and say chiro­practic is not a treatment for Huntington’s disease, Parkinson’s or Alzheimer’s? They’re nervous system disorders too.

Why might parents find chiro­practic helpful if it’s not because chiropractic works? I reckon our old friends ­confirmation bias, cognitive dissonance, the Hawthorne Effect and placebo effects can take the credit. Which is why testimonials are an issue too – it costs me enough to go to a conventional medical doctor, but there is scientific evidence to show antibiotics reduce infection, for example.

I’m not opposed to people visiting their local back adjuster – a placebo effect can be a positive effect. Last year, German psychiatrist Paul Plener told me placebos are routinely the first treatment prescribed by German GPs. Their clients know this and are okay with it. The difference is nobody’s making a miracle claim or violating their own ethics and the law.

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