This article was originally published in The New Scientist
For many people, chiropractic appears almost mainstream. Some chiropractors even call themselves “doctor”. In the UK, chiropractors are regulated by statute, and in the US they like to be seen as primary care physicians. It is therefore understandable if people hardly ever question the evidential basis on which this profession rests.
The origins of chiropractic are surprising and rather spectacular. On 18 September 1895 Daniel Palmer, a “magnetic healer” practising in the American Midwest, manipulated the spine of Harvey Lillard, a janitor who had been partially deaf since feeling “something give in his back”. The manipulation apparently cured Lillard of his deafness. Palmer’s second patient suffered from heart disease, and again spinal manipulation is said to have effected a cure. Within a year or so, Palmer had opened a school, the first of many, and the term he coined, “chiropractic”, was well on its way to becoming a household name.
The only true cure
Palmer convinced himself he had discovered something fundamental about human illness and its treatment. According to Palmer, a vital force – he called it the “Innate” – enables our body to heal itself. If our vertebrae are not perfectly aligned, the flow of the Innate is blocked and we fall ill. Chiropractors speak of these misalignments as “subluxations” (in conventional medicine, a subluxation means merely a partial dislocation). The only true cure is to realign the vertebrae by manipulating the spine, and in the logic of chiropractic it follows that all human illness must be treated with spinal manipulations. Many chiropractors also assert that we need regular “maintenance care” even when we are not ill so that subluxations can be realigned before they cause a disease. In the words of Palmer “95 per cent of all diseases are caused by displaced vertebrae, the remainder by luxations of other joints”.
All diseases are caused by ‘subluxations’ blocking the flow of the ‘Innate’
This bit of history is important because it explains why many chiropractors treat all sorts of conditions, not just back pain. In fact, in the early days, back pain was not an issue for chiropractors at all. Today they are divided into roughly three camps. 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.
If you find this hard to believe, here is the evidence. A 2004 survey by the UK General Chiropractic Council revealed that most chiropractors believe they can treat asthma (57 per cent), digestive disorders (54 per cent), infant colic (63 per cent), menstrual pains (63 per cent), sport injuries (90 per cent), tension headaches (97 per cent) and migraine (91 per cent). According to a 2007 survey, 69 per cent of all UK chiropractors see themselves as more than just back specialists, and 76 per cent consider Palmer’s original concepts to be “an important and integral part of chiropractic”.
So, are they right? 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. We therefore need to ask, how good is chiropractic spinal manipulation in treating anything?
The answer is not clear-cut. For back pain, there is some encouraging evidence. Chiropractic manipulations have been shown in several clinical trials to be as effective as standard treatments. One needs to know, however, that standard care is not very effective for bad backs, and studies that adequately control for placebo effects tend to arrive at less positive conclusions. 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” (Journal of Pain and Symptom Management, vol 22, p 879).
For virtually all the other conditions which chiropractors treat, where rigorous trials have been done, the evidence is weaker. In some cases, the most reliable studies have found that spinal manipulation is ineffective.
Chiropractors and many of their professional associations often claim otherwise, but a few do acknowledge this problem. In 2001, one team of chiropractors looked at this issue, and their conclusion was blunt: “The largest professional associations… make claims for the art of chiropractic that are not currently justified by available scientific evidence”. Since then, several investigators have come to similar conclusions.
The issue is not just whether chiropractic treatments work. There is also the question of the safety of chiropractic spinal manipulation, a matter that few people seem to be aware of. Several big studies have shown that a large proportion of patients experience side effects after receiving chiropractic spinal manipulation. Luckily these complaints – mostly pain – are not normally very severe and are usually gone after a day or two.
There have, however, been several hundred cases of potentially very serious complications associated with this treatment. Extreme chiropractic manipulation of the neck can damage one of the two vertebral arteries that run roughly parallel to the upper spine and supply part of the brain. The consequence of such a “vascular accident” can be a stroke, and several deaths are on record. Such disastrous events are, of course, rare; this is one reason why it is difficult to investigate this phenomenon systematically and not all studies show the same result.
In the book I co-wrote with Simon Singh, Trick or Treatment? Alternative medicine on trial, we dedicate a chapter to chiropractic. After weighing all the evidence, our conclusions were not flattering: “Warning: this treatment carries the risk of stroke and death if spinal manipulation is applied to the neck. Elsewhere on the spine, therapy is relatively safe. It has shown some evidence of benefit in the treatment of back pain, but conventional treatments are usually equally effective and much cheaper. In the treatment of all other conditions chiropractic therapy is ineffective except that it might act as a placebo.”
Simon later wrote an article in The Guardian newspaper about chiropractic. In it, he quoted from the website of the British Chiropractic Association which, at the time, made fairly clear claims that chiropractors can effectively treat a whole range of childhood diseases, including asthma. The evidence for treatment of this condition is less than weak: no fewer than three controlled trials have found that chiropractic spinal manipulation has no beneficial effect. The best of these studies, published in The New England Journal of Medicine, concluded that “the addition of chiropractic spinal manipulation to usual medical care provided no benefit”.
For alerting the public to all of this, and possibly preventing harm to unsuspecting children, Simon deserves much credit. Instead, he is being sued for libel by the British Chiropractic Association. I think this is a serious issue that raises two crucial questions. Is it acceptable that scientists and journalists are restricted in their criticism by the legal muscle of those who are being criticised? And is it acceptable that professional bodies, such as the British Chiropractic Association – or indeed any other organisation – are able to make therapeutic claims that are not supported by scientific data? I leave it to the reader to decide.
Edzard Ernst is professor of complementary medicine at the Peninsula Medical School in Exeter, UK. In his investigations of alternative therapies, he has found only about 5 per cent are supported by scientific evidence; the rest are either ineffective or have not been tested properly.
See also: McTimoney Chiropractors told to take down their web sites.