Lewith lashes out
Posted by apgaylard on June 20, 2009
From his letter published in this week’s New Scientist it is clear that Professor George Lewith doesn’t like Edzard Ernst’s recent opinion piece on Chiropractic. However, it is just as clear that Lewith is prepared to use fallacious reasoning and debunked statistics, among other things, to support his argument.*
It’s not as though he even manages to properly engage with Ernst’s criticisms. Through cherry picking and a meticulous avoidance of published evidence he first constructs then attacks a straw man.
His opening accusation is that, “[…] Ernst fails to give a balanced view of Chiropractic”.** Is this a true reflection of what Ernst wrote? Well, Ernst’s article maps out the origins of Chiropractic, and then describes three major schools:
“One adheres religiously to Palmer’s gospel – indeed, at one stage Palmer considered establishing Chiropractic as a religion. Another has moved on and now employs a range of non-drug treatments in addition to manipulations, mainly for treating back pain. The third group is situated somewhere in between these two extremes and, at least occasionally, treats many conditions other than back pain.”
This seems pretty balanced to me: he does not tar all chiropractors with the same brush and acknowledges that the practise has, at least for one of the schools, moved on from strict observance of the teachings of Palmer.
He does use the history of Chiropractic to explain why chiropractors treat conditions other than back pain. This is backed up with evidence – a GCC survey no less – to show how widespread the belief is among UK chiropractors that they can treat non-spinal conditions.
It is also important to note that Ernst does not dismiss Chiropractic on the basis of its pre-scientific origins:
“Palmer’s concepts of the Innate and subluxation are pre-scientific and wacky, but that in itself needn’t mean that the treatment is not helpful.”
Again, I’d say that is generous. Ernst sets aside plausibility and focuses on the research evidence. He very fairly discusses what he calls, “some encouraging evidence” on the Chiropractic treatment of back pain; balancing this against the limited effectiveness of “standard care” for back pain and the influence of “placebo effects” before he cites a review:
“When my team in Exeter reviewed data from these more rigorous trials we concluded that “spinal manipulation is not associated with clinically relevant specific therapeutic effects” (Ernst and Harkness, 2001)
Again, very balanced, measured and supported by cited evidence. However, I get the impression that this is probably not the conclusion that Lewith would favour.
After making the accusation that Ernst’s piece is “unbalanced”, Lewith offers an evidence-free justification for contemporary Chiropractic:
“Since its origins in the middle of the 19th century, Chiropractic has changed considerably. It no longer espouses a vitalistic philosophy.“
I’m not sure that Lewith can really speak for Chiropractic as a whole, but this statement is surprising. First, Ernst actually cited a statistic from Pollentier and Langworthy (2007) that beggars Lewith’s contention: “76 per cent consider Palmer’s original concepts to be “an important and integral part of Chiropractic”.” So, there is good evidence to suggest that Chiropractic as a whole, at least in the UK, is still in thrall to Palmer’s pre-scientific philosophy. Conversely, Lewith merely offers a sweeping opinion.
“No matter what you call it, living things have it and dead things don’t. It is a force that animates, adds life, grows, organises and evolves. Each cell has it, each organ has it, every living thing has it. Chiropractors call this Force Innate Intelligence.”
It’s only fair to point out that this site belongs to a follower of the fringe “network Chiropractic” philosophy. However, the website of the mainstream Wokingham Chiropractic Centre (Cached URL) has this to say about Chiropractic:
“Chiropractic originated in the United States in 1895. It was founded by D.D.Palmer.
Although some of his writing seems dated one hundred years on, the principles upon which he based Chiropractic are unchanged.
These basic tenets are as follows:
The human body has an innate ability to regulate, repair and heal itself. D.D. Palmer called this ‘innate intelligence’.
The nervous system allows the brain to monitor and control the rest of the body. The spine and cranium (skull) provide physical support and protection for the brain and central nervous system.
Poor function of the spinal and cranial systems interferes with the nervous system’s ability to control and monitor the rest of the body. This limits the body’s ability to regulate, repair and heal itself.
In a nutshell, poor spinal and cranial function directly compromises the health of the body. Chiropractic aims to promote health by restoring the function of the skeletal and cranial structures. It aims to remove the impediments which limit the body’s innate healing ability. Chiropractic does not “cure” anything. It respects the body’s innate intelligence. With this in mind, the chiropractor works in partnership with the person receiving Chiropractic care.”
So, in reality it seems that there is a strong case for saying that vitalism is alive and well within mainstream Chiropractic in the UK. It’s a shame that Lewith failed to engage with this evidence – even though it was part of the article that he is objecting to.
Now Lewith goes on the offensive, offering a fallacious notion of equivalence between real medicine and Chiropractic:
“Equally, conventional medicine has changed and no longer bleeds dehydrated cholera patients to death. “
No, not “equally”: medicine has been transformed by the discovery and adoption of effective treatments for a wide range of conditions, some of which were previously fatal. In contrast we have seen that three quarters of UK chiropractors still value a debunked philosophy. Add to this that the best case anyone seems to be able to make for Chiropractic is that it works as well for back pain as other treatments that don’t work very well. There is no equivalence here.
Not done with striking one false-equivalence, Lewith throws in another:
“The evidence base for Chiropractic is limited and more research is needed; much the same is true of general practice, where perhaps only 15 to 20 per cent of the interventions used are based on sound evidence. “
No, general practise does not have an evidence base as limited as Chiropractic. There is no equivalence or near equivalence here: Chiropractic does not come close. At this point Lewith does try to support his contention with some statistics; it’s a shame that they are misleading.
The claim that only 15 to 20 per cent of conventional medical interventions are based on sound evidence is commonly made. Steven Novella has discussed the claim in detail.
“The 15% figure comes from a small survey of primary practice offices in the north of England conducted in 1961 – that’s right, almost half a century ago. Further, the survery was never intended to assess the degree to witch primary practices were evidence-based, but rather was looking at whether treatments were “specific” from the point of view of insurance reimbursement. So the 15% figure is misrepresented and half a century out of date.”
What is the real number? It is very difficult to say and, consequently, estimates vary. However, Novella quotes an assessment made by the late Robert Imrie***, who came to the conclusion that:
“[…] published results show an average of 37.02% of interventions are supported by RCT (median = 38%). They show an average of 76% of interventions are supported by some form of compelling evidence (median = 78%).”
An on-line resource guide provided by Sheffield University cites a study which is directly relevant to this issue (Gill et al, 1996). This study assessed 122 consecutive consultations in a general medicine training practice and found that 81% of the medical practice was evidence based. (Either RCTs or, “convincing non-experimental evidence”.)
There is definitely some uncertainty in these estimates, however the fantasy un-referenced figure plucked out of the air by Lewith is clearly wrong. The use of this bad statistic may suit his argument; but is this approach appropriate for a Professor of Health Research?
It is worth noting that even if only 15 to 20 percent of medical interventions used in general practise were based on “sound evidence” this is would be still make it vastly superior to Chiropractic practise. Only the treatment of back pain is supported by anything approaching “sound evidence”. None of the childhood ailments at the centre of this controversy are.
“Chiropractors do not claim incontrovertible evidence for the use of Chiropractic in children, only that there is evidence for their claims.”
I will concede that this sentence is probably true. However the “claims” for which these chiropractors assert they have evidence centres on treating children by spinal manipulation for: colic, asthma, nocturnal enuresis, and otitis media. There is no “only” about this: the claimed “evidence” is being used to justify medical interventions on children. This should require more than the handful of generally small, poor quality studies cherry-picked by Chiropractic organisations like the BCA.
For example, I’ve looked in detail at the evidence for Chiropractic manipulation ‘helping’ children who wet the bed. It is, at best, “weak”. There is not a jot of “sound evidence” that Chiropractic can help with this condition.
I must say that I’m not impressed by Lewith’s letter. It appears to ignore much of what Ernst actually wrote. It fails to present any evidence to back up the claims I’ve examined. It overlooks important evidence that contradicts some of the main points it makes. Finally, Lewith succumbs to the temptation to indulge in fallacious argument.
This letter certainly does not present either a balanced view of Chiropractic or the arguments made by its critics. I hope that Ernst gets a chance to expose this shallow critique in print****. It would be a shame for unwary New Scientist readers to be misled by this unworthy epistle.
This does not constitute medical advice. If you need that please consult a medical doctor.
*** Imrie provided some interesting evidence in a series of rapid responses on the BMJ website in 1999. He enters into a frustrating debate with proponents of acupuncture here, here, here, here, here and here.
****Ernst provides an interesting response in a Letter published in the New Scientist on 25th June 2009. In an “Open letter to all UK chiropractors” he asks them to state plainly where they stand on the treatment of non-spinal ailments, picking one of:
“you no longer hold that chiropractic is an effective treatment for non-spinal conditions like asthma, you admit that the inclusion of treatment of non-spinal conditions in chiropractic means that it can no longer be considered an evidence-based profession, or you can provide good evidence that chiropractic can treat non-spinal conditions.”
Ernst E, Harkness E. Spinal Manipulation A Systematic Review of Sham-Controlled, Double-Blind, Randomized Clinical Trials. Journal of Pain and Symptom Management. 2001 October;22(4):879–889. Available from: http://dx.doi.org/10.1016/S0885-3924(01)00337-2.
Gill P, Dowell AC, Neal RD, Smith N, Heywood P, Wilson AE. Evidence based general practice: a retrospective study of interventions in one training practice. BMJ. 1996 March;312(7034):819–821. Available from: http://www.bmj.com/cgi/content/full/312/7034/819
Pollentier A, Langworthy J. The scope of Chiropractic practice: A survey of Chiropractors in the UK. Clinical Chiropractic. 2007 September;10(3):147–155. Available from: http://dx.doi.org/10.1016/j.clch.2007.02.001.
25th June 2009. Note referencing Ernst’s response in the New Scientist added.
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