Behold the jot of evidence

October 17th, 2009 by Ben Goldacre in bad science, legal chill, libel | 65 Comments »

Ben Goldacre, Saturday 17 October 2009, The Guardian

For those with the finances to try to silence their critics, this has been a week of spectacular own goals. Trafigura has loudly advertised the report on the dumping of toxic waste in Africa by taking out a super-injunction through Carter-Ruck. And on Wednesday Simon Singh, the science writer being sued by the British Chiropractic Association, won his right to an appeal.Briefly, Singh was sued by the BCA over an article in the Guardian in which he criticised chiropractors for claiming they can treat children’s colic, sleeping and feeding problems, ear infections, asthma and prolonged crying, by manipulation of the spine. He said these interventions were “bogus”, with “not a jot of evidence”. Before this case most people hadn’t really noticed chiropractors. Now the internet is awash with reviews of the evidence and its flaws, so this is a good time to revisit the evidence.

Richard Brown, vice-president of the BCA, writes in the British Medical Journal (the article is open-access) that there is “substantial evidence for the BCA to have made claims that chiropractic can help various childhood conditions”. He provided references to 19 academic papers. These have now been examined and effectively demolished in a response by Edzard Ernst, professor of complementary medicine at the Peninsula medical school, Exeter. I am happy to see that someone else has done this work, and I will now walk you through his summary.

Four of the BCA’s references do not contain data about chiropractic treatment for the conditions being discussed, and so are irrelevant. Eight refer to types of evidence that can tell us little about whether a treatment works: questionnaire surveys, case reports and so on. That’s 12 of the 19 references out already.

Among the rest, we are given a small pilot study, by Mercer and Nook, but it is unpublished, and the short conference summary that is available does not have enough information for anyone to know whether their methods were sound.

We are given a trial by Wiberg et al, in which 50 children with colic got either chiropractic or dimethicone: they found less crying in the chiropractic group, but because the babies and parents could not be blinded – they knew which treatment they were getting – even the researchers themselves felt this improvement might be due to a placebo response, or other non-specific effects unrelated to the chiropractic treatment, such as extra attention.

Hawk et al have a systematic review of various types of spinal manipulation for non-spinal conditions and look at the treatment of asthma, otitis and colic. Systematic reviews examine trials and summarise them. They give a positive conclusion for the treatment of asthma, but this relies on a study about osteopaths manipulating the ribs, so that’s not relevant.

They are also positive about colic, to be fair, but, for evidence, they rely on the flawed and unblinded study by Wiberg, described in the previous paragraph. This review therefore adds nothing.

There is a Cochrane review looking at various treatments for bed-wetting, and Cochrane reviews are high-quality summaries of the evidence, as you will know. This one found two trials of chiropractic, which were not of high quality – in fact, the authors described them as “weak evidence”. So that’s not good.

Browning did a trial – which was published after Singh’s article – comparing spinal manipulation with occipitosacral decompression. Both are dubious treatments, and the trial found no difference between them. So both may be effective, or both may just be equally ineffective; either way, no prize.

But most interesting are the studies which the BCA chose not to mention: three randomised controlled trials and two systematic reviews, arguably the strongest evidence, were omitted. The BCA is aware of these studies, because it has specifically commented on other work based on them. So why did they not explicitly reference them? I don’t know. But they are negative papers, which failed to show that chiropractic was effective; while quoting irrelevant papers, questionnaires, case studies and weak trials, the BCA ignored these higher-quality studies, with their unflattering results.

There are huge, endless debates to be had on our libel laws, on the risks they pose to the public by stifling access to information, and on the changes that could be made. But, for today, know this: there is no good evidence that chiropractic is effective for the conditions claimed by the BCA, for the reasons you now know. Shout it from the highest rooftop, when you tell your friends about Trafigura, because, until the law changes, the strongest disincentive to this effect is a very close examination of the companies involved.

If you like what I do, and you want me to do more, you can: buy my books Bad Science and Bad Pharma, give them to your friends, put them on your reading list, employ me to do a talk, or tweet this article to your friends. Thanks! ++++++++++++++++++++++++++++++++++++++++++

65 Responses

  1. Colchicine said,

    October 26, 2009 at 7:28 pm


    You appear to bestow near mythical healing powers on the allopathic osteopaths. This seems over zealous considering they perform the same examinations as other, lesser, osteopaths and chiropractors and treat in a surprisingly similar manner with similar success rates (so much so I suspect you couldn’t tell the difference). Do you happen to know one very well?

    Also, it is definitely considered good research practice to draw widely from similar fields – and you should be worried if this:
    “As evidenced by the BCA ‘borrowing’ evidence of effectiveness from osteopathic medicine research.” was not happening, especially as they are doing pretty much the same things, even the Medical Osteopaths.

    I think you are wrong in your insinuation that there is no research going on in the chiropractic world – any proof? I’d like to see the numbers of papers produced by chiros against those produced by osteopaths.

  2. Bloodvassal said,

    October 26, 2009 at 11:45 pm

    >Meade TW, Dyer S et al 1990. Low Back Pain of >Mechanical Origin. Randomised Comparison of >Chiropractic and Hospital Outpatient Treatment, BMJ >300: 1431-37;
    >and the follow up study:
    >Meade T W, Dyer S et al 1995. Randomised Comparison of >Chiropractic and Hospital Outpatients Management for >Low Back Pain Results from Extended Follow Up, BMJ 311: >349->351.

    #50 I don’t know much about chiropractic or for that matter physiotherapy but I do know a wee bit about experimental layout it seems to me that this wasn’t a terribly well balanced study on a number of levels.

    The first appears to be that there is absolutely no control for exactly what therapy was given to any individual patient. Indeed, there is no mention of what exact therapy was given. How can we compare?

    Second, having sat in NHS waiting rooms and been treated in an NHS ward and as an outpatient, the biggest identifiable experimental modifier appears to be where the therapy took place. That is, a private chiropracter’s office or an NHS hospital room. This study isn’t truly a comparison of therapy, which is the whole point of your post, it’s a comparison of public versus private.

    There also appears to be nearly a 25% difference numbers of long term questionaire returns, with the highest number coming from those receiving chiropractic. And the bias further creeps in with the fact that many of the patients being given chiropractic were previously users of chiropractic services. Indeed the authors themselves say:
    “Those referred by chiropractors consistently derived more benefit from chiropractic than those referred by hospitals.”

    Already predisposed to thinking that it benefits them these patients confirm their belief in this study.. confirm their belief… hmm belief… yes, confirmed their faith in the therapy, in their healing.. their faith in their healing… faith healing… wow.

    Ultimately I think that the authors themselves sum it up nicely in their own Key Message from the paper. Their conclusion is that treatment in a chiropractic office is superior to treatment in a hospital but why? Authors’ Key message:

    “Chiropractic seems to be more effective than hospital management, possibly because more treatments are spread over longer time periods”

    They see the practitioner more. Private office nicer than cold hospital, chiropractic practitioner has more time to talk than physiotherapist. And this is the big evidence of the benefits of chiropractic as opposed to conventional treatment? Here’s a small unsubstantiated, unreferrenced, unscientific comment… repeat that study with chiropractic in an NHS hospital, or physiotherapy in a private clinic and see those statistical differences fall away.

  3. Bloodvassal said,

    October 27, 2009 at 12:17 am

    Oh Dear…. Triano et al. a study of patients actively seeking chiropractic then comparing those who got it (HVLA in the paper) with those who essentially didn’t (HVLF), and finally those who were shown a powerpoint presentation which told them to sit up straighter. Again.. those who went there expecting to receive chiropratic and got it, felt better than those who didn’t.

    You know I really didn’t have an opinion about chiropratic until I read these papers.

  4. Bloodvassal said,

    October 27, 2009 at 12:28 am

    In a new segment called Seriously. Seriously.. Assendelft et al 2003. Spinal manipulative therapy for low back pain. A meta-analysis of effectiveness relative to other therapies.

    Independent and blinded meta-analysis no less.

    Authors conclusion… nicely summarised in the Abstract:

    CONCLUSIONS: There is no evidence that spinal manipulative therapy is superior to other standard treatments for patients with acute or chronic low back pain.

    Does this really help a pro-chiropractic argument? Seriously? SERIOUSLY?

    I was only going to post a sentence when I first read the blog but dude… seriously?

  5. mikewhit said,

    October 27, 2009 at 1:42 pm

    “conventional, allopathic, medical treatment.”

    Isn’t “allopathic” (different feeling) used in opposition to “homoeopathic” (same feeling) – in which case what’s it doing in a discussion about rubbing people’s backs ?

  6. mikewhit said,

    October 27, 2009 at 1:46 pm

    “if anything conventional medicine’s done nothing but favours to a profession which has done little to prove itself besides pulling a Roman Polanski in England’s libel courts.”

    I didn’t know that the lady who was subject to “lymphatic stimulation” was under age …

  7. Dr Aust said,

    October 27, 2009 at 11:10 pm

    Nice exposition of the possible confounding effects, Bloodvassal.

    Anyone still in doubt as to the resounding feebleness of the research that chiropractors have attested to support their therapeutic claims should go back to Ben’s post from 29th July, where he links to many of the bloggers who “deconstructed” the BCA’s “plethora of evidence” (i.e., the best published research they could come up with for chiropractic for children’s ailments, which wasn’t much):

    – the 7th para down is the one with the links.

    Links to many of the same blogs, and some others, can also be found at the Lay Scientist site:

    Re chiropractic for lower back pain, the only indication for which it has any real plausibility, there is not much evidence there either. Some studies show it working about as well as other things, but the key point is that NONE of the interventions or treatments work well. (Note that that includes the conventional stuff). Prof David Colquhoun has written about this a lot. Since chiropractic is expensive, and is based upon a “business model” of convincing you you have to keep coming back for more “adjustment”, it would not be the option of choice for back problems, IMHO. If you want back manipulation, physiotherapy is more accessible, certainly via the NHS in the UK, and comes free of all the chiropractic mumbo-jumbo. For a GP view saying something similar see:

    Re the cost of chiropractic, my other half, who is a conventional doctor and sees a lot of patients with back pain, has come across patients forking over something like a third of their monthly pay to be “adjusted” weekly by a chiropractor. I think personally that we in the UK are very fortunate to have escaped the US situation where chiropractors are able to present themselves as “primary healthcare professionals”.

    Finally, there is a good summary regarding chiropractic claims in general at Lay Scientist here:

    PS Sorry not to embed the links to make this look nicer, but it hasn’t been working recently.

  8. Squander Two said,

    October 28, 2009 at 8:35 pm

    Dr Aust,

    > Since chiropractic is expensive, and is based upon a “business model” of convincing you you have to keep coming back for more “adjustment” …

    As I mentioned above, I’ve yet to come across a chiropractor who uses that business model. Every one I’ve seen and every one anyone I know has seen has taken the attitude “You’re cured! Yay! You don’t need me any more! Brilliant!” I’m sure some of them are using that business model, but to say that the entire field is based on it is demonstrably wrong.

    I wouldn’t call it expensive, either. The average GP’s salary is now over £100k, so a quick back-of-the-envelope calculation shows that GPs are charging at least £50 an hour. Some are making more like £250k, which comes to about £120 an hour. And of course your GP won’t provide any back-pain treatment; they’ll either prescribe you drugs which cost money or refer you to another medic who’ll cost money. Chiropractors are about £30 per 20-minute session. So not cheap, but certainly not expensive, either. Even if you think they provide nothing more than glorified massage, their rates still compare favourably to masseurs’.

  9. mikewhit said,

    October 29, 2009 at 3:24 pm

    “The average GP’s salary is now over £100k”:
    “Many general practitioners (GPs) are self employed and hold contracts … Salaried GPs employed directly by PCTs earn between £53,249 to 80,354, dependent on, among other factors, length of service and experience.”
    “The average salary for a Gp in the UK is: £63,688”

  10. Dr Aust said,

    October 30, 2009 at 4:49 pm

    MikeWhit has already made the point about GP’s salaries. The higher figures are for particular sub-classes of GP partners, who effectively run businesses as well as being GPs. (They do this, now on “payment by results”, because the Govt insisted that this “incentivised” system was how they should do it, BTW).

    Salaried GPs, of whom there are more and more, earn far less, though no-one is saying they are poorly paid.

    A quick look around reveals private GP rates in the UK run around £ 50-100 for a 15 min consultation, and £ 25 for 5 min on the phone. Of course, the NHS does not charge you for anything, including phone calls and home visits (if needed), let alone dunning you for more money if you over-run your slot.

    So… even if you assume top of range salaried GP (£ 80K), and 37.5 hrs /wk (which I predict will never be that little, as surgeries always overrun, and they do home visits, phone calls, paperwork etc etc.), and 48 working wks/yr, you can back-of-the-envelope to £ 50-60 / hr.

    The private sector charges four times that, to see a doctor you may not know from Adam and who has no B/G info on you.

    Incidentally, the system of GPs as gatekeepers to secondary (hospital) care will work better (better diagnosis, less unnecessary referral) when the GPs are more skilled and more experienced. Which probably also means better paid in any business model.

    It is the pretty much universal verdict of academic health economists who have studied UK general practice that it represents one of the greatest healthcare bargains you are ever likely to get offered. In 2004 (admittedly a while back) the costs to the taxpayer were estimated as between £ 12 and £ 55 per patient per year (v. young, or old and sick, patients cost more).

    I’m glad Squander Two (Comment 58) has found some honest chiropractors. Unfortunately, they are not all like that. My other half saw a patient recently who had, for several months, been forking over a third of her monthly take-home pay to a chiropractor for weekly “adjustments” to help with lower back problems. (It wasn’t helping.) When the patient told the chiropractor she had a non-spine related problem he helpfully told her he could sort that out too. Assuming she could paid for the extra sessions, of course.

  11. Dr Aust said,

    October 30, 2009 at 6:00 pm

    PS Oops – sorry, same anecdote again, didn’t re-read my previous post. My bad.

    Much more of this story-telling and I will have to set up in business as an Alternative Practitioner.

  12. mikewhit said,

    November 2, 2009 at 1:29 pm

    “My bad.”

    Your bad what ?
    … bad back ?!

  13. Squander Two said,

    November 2, 2009 at 8:08 pm

    Just to be clear, I wasn’t complaining that GPs earn too much. I was just comparing. If you want to claim that chiropractice is expensive, “Compared to what?” seems like a reasonable question. I was unaware that there were two lots of figures for different types of GPs. However, using your lower figures, and taking into account that, as I said, GPs’ costs are only the start of the cost of a medical treatment, I still don’t think chiropractors are expensive.

    Not sure why you’re getting into the whole NHS-versus-private thing, but, since you are…

    > The private sector charges four times that, to see a doctor you may not know from Adam and who has no B/G info on you.

    Eh? Surely, whether I’m on the NHS or going private, I can opt to see a doctor who’s never heard of me. If I want to go private, I can get a private GP and see that same private GP every time, until they know me. If I move from the NHS to a private GP, I can have my records transferred. I can move from a private GP to an NHS GP, and thus end up seeing someone who doesn’t know me from Adam and doesn’t have any of my records unless they get hold of my records. Lots of doctors work both on the NHS and privately, so I even have the option of seeing exactly the same doctor via the two different payment mechanisms. That doctor will not magically forget all about me if I start seeing him privately. I don’t think your assertion that NHS GPs know their patients whilst private ones don’t holds much water.

    > Of course, the NHS does not charge you for anything, including phone calls and home visits (if needed)

    People in this thread are complaining that chiropractice is covered by some health insurance firms, so it makes as much sense to compare it to private as to the NHS. Who’s picking up the tab isn’t the issue.

    Secondly, the NHS charge a very large amount of money. The fact that I get charged the money before it reaches my payslip rather than after it reaches my bank account doesn’t mean it doesn’t exist.

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  15. fiolondon said,

    December 8, 2009 at 1:04 pm


    I am a bit scared of some of the people on this forum – someone earlier asked what evidence there was that Thalidomide was harmful!!!! No-one bothered to mention so I slightly wonder whether it is worth me making the following points……

    Way up the top, Dr Vincent said
    “The chiropractic profession does not have access to the vast sums of money available to the medical profession and so finds it very difficult to undertake large population based studies.”

    Which seems to have been roundly dismissed by all! At the risk of being lambasted I thought it was an interesting point.

    Mainstream medical research is sponsored by pharmaceutical and surgical manufacturers, government and big name charities. Privately sponsored research actually pays people to participate and studies are replicated to get the right answer and cherry picked for publication. (My husband used to be a pharmaceutical rep – apologies for the use of an anecdote rather than a referenced RCT there folks.)

    Anyway, in contrast, I think that Chiropracters are self employed sole traders working on their own. They might each see a maximum of 70 patients a week if they were fully booked and never ate lunch. If one dedicated individual decided to go for it and get a sample of say, 3000 people – which does not sound like a lot – it would take an about a year’s worth of appointments. To do a full RCT the treatment would have to be offered free of charge. That adds up to an individual practicioner going for a year without pay (before anyone suggests spreading it out over a longer period it is still the same amount!). What individual is going to be able to afford to do that?

    I’d say Dr Vincent has a point.

    . So to get enough data they would presumably have to sacrifice their personal income over quite a period.