Download Lectures on Biostatistics (1971). Corrected and searchable version of Google books edition
Download review of Lectures on Biostatistics (THES, 1973).
Michael Marmot
| The Prince of Wales’ Foundation for Integrated Health (FiH) is a propaganda organisation that aims to persuade people, and politicians, that the Prince’s somewhat bizarre views about alternative medicine should form the basis of government health policy.
His attempts are often successful, but they are regarded by many people as being clearly unconstitutional. |
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The FiH’s 2009 AnnualConferen ce conference was held at The King’s Fund, London 13 – 14 May 2009. It was, as always, an almost totally one-sided affair devoted to misrepresentation of evidence and the promotion of magic medicine. But according to the FiH, at least, it was a great success. The opening speech by the Quacktitioner Royal can be read here. It has already been analysed by somebody who knows rather more about medicine than HRH. He concludes
“It is a shocking perversion of the real issues driven by one man; unelected, unqualified and utterly misguided”.
We are promised some movie clips of the meeting. They might even make a nice UK equivalent of “Integrative baloney @ Yale“.
This post is intended to provide some background information about the speakers at the symposium. But let’s start with what seems to me to be the real problem. The duplicitous use of the word “integrated” to mean two quite different things.
The problem of euphemisms: spin and obfuscation
One of the problems of meetings like this is the harm done by use of euphemisms. After looking at the programme, it becomes obvious that there is a rather ingenious bit of PR trickery going on. It confuses (purposely?) the many different definitions of the word “integrative” . One definition of “Integrative medicine” is this (my emphasis).
” . . . orienting the health care process to engage patients and caregivers in the full range of physical, psychological, social, preventive, and therapeutic factors known to be effective and necessary for the achievement of optimal health.”
That is a thoroughly admirable aim. And that, I imagine, is the sense in which several of the speakers (Marmot, Chantler etc) used the term. Of course the definition is rather too vague to be very helpful in practice, but nobody would dream of objecting to it.
But another definition of the same term ‘integrative medicine’ is as a PR-friendly synonym for ‘alternative medicine’, and that is clearly the sense in which it is used by the Prince of Wales’ Foundation for Integrated Health (FIH), as is immediately obvious from their web site.
The guide to the main therapies supports everything from homeopathy to chiropractic to naturopathy, in a totally uncritical way. Integrated service refers explicitly to integration of ‘complementary’ medicine, and that itself is largely a euphemism for alternative medicine. For example, the FIH’s guide to homeopathy says
“What is homeopathy commonly used for?
Homeopathy is most often used to treat chronic conditions such as asthma; eczema; arthritis; fatigue disorders like ME; headache and migraine; menstrual and menopausal problems; irritable bowel syndrome; Crohn’s disease; allergies; repeated ear, nose, throat and chest infections or urine infections; depression and anxiety.”
But there is not a word about the evidence, and perhaps that isn’t surprising because the evidence that it works in any of these conditions is essentially zero.
The FIH document Complementary Health Care: A Guide for Patients appears to have vanished from the web after its inaccuracy received a very bad press, e.g. in the Times, and also here. It is also interesting that the equally widely criticised Smallwood report (also sponsored by the Prince of Wales) seems to have vanished too).
The programme for the meeting can be seen here, for Day 1, and Day 2
Conference chair Dr Phil Hammond, GP, comedian and health service writer. Hammond asked the FIH if I could speak at the meeting to provide a bit of balance. Guess what? They didn’t want balance.
09:30 Opening session
Dr Michael Dixon OBE
09:30 Introduction: a new direction for The Prince’s Foundation for Integrated Health and new opportunities in integrated health and care. Dr Michael Dixon, Medical Director, FIH
Michael Dixon is devoted to just about every form of alternative medicine. As well as being medical director of the Prince’s Foundation he also runs the NHS Alliance. Despite its name, the NHS Alliance is nothing to do with the NHS and acts, among other things, as an advocate of alternative medicine on the NHS, about which it has published a lot.
Dr Dixon is also a GP at College Surgery, Cullompton, Devon, where his “integrated practice” includes dozens of alternative practitioners. They include not only disproven things like homeopathy and acupuncture, but also even more bizarre practitioners in ‘Thought Field Therapy‘ and ‘Frequencies of Brilliance‘.
To take only one of these, ‘Frequencies of Brilliance’ is bizarre beyond belief. One need only quote its founder and chief salesperson.
“Frequencies of Brilliance is a unique energy healing technique that involves the activation of energetic doorways on both the front and back of the body.”
“These doorways are opened through a series of light touches. This activation introduces high-level Frequencies into the emotional and physical bodies. It works within all the cells and with the entire nervous system which activates new areas of the brain.”
“Frequencies of Brilliance is a 4th /5th dimensional work. The process is that of activating doorways by lightly touching the body or working just above the body.”
“Each doorway holds the highest aspect of the human being and is complete in itself. This means that there is a perfect potential to be accessed and activated throughout the doorways in the body.”
Best of all, it can all be done at a distance (that must help sales a lot). One is reminded of the Skills for Health “competence” in distant healing (inserted on a government web site at the behest (you guessed it) of the Prince’s Foundation, as related here)
“The intent of a long distance Frequencies of Brilliance (FOB) session is to enable a practitioner to facilitate a session in one geographical location while the client is in another.
A practitioner of FOB that has successfully completed a Stage 5 Frequency workshop has the ability to create and hold a stable energetic space in order to work with a person that is not physically present in the same room.
The space that is consciously created in the Frequencies of Brilliance work is known as the “Gap”. It is a space of nonlinear time. It contains ”no time and no space” or respectively “all time and all space”. Within this “Gap” a clear transfer of the energies takes place and is transmitted to an individual at a time and location consciously intended. Since this dimensional space is in non-linear time the work can be performed and sent backward or forward in time as well as to any location.
The Frequencies of Brilliance work cuts through the limitations of our physical existence and allows us to experience ourselves in other dimensional spaces. Therefore people living in other geographic locations than a practitioner have an opportunity to receive and experience the work.
The awareness of this dimensional space is spoken about in many indigenous traditions, meditation practices, and in the world of quantum physics. It is referred to by other names such as the void, or vacuum space, etc.”
This is, of course, preposterous gobbledygook. It, and other things in Dr Dixon’s treatment guide, seem to be very curious things to impose on patients in the 21st century.
Latest news. The Mid-Devon Star announces yet more homeopathy in Dr Dixon’s Cullompton practice. This time it comes in the form of a clinic run from the Bristol Homeopathic Hospital. I guess they must be suffering from reduced commissioning like all the other homeopathic hospitals, but Dr Dixon seems to have come to their rescue. The connection seems to be with Bristol’s homeopathic consultant, Dr Elizabeth A Thompson. On 11 December 2007 I wrote to Dr Thompson, thus
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In March 2006, a press release http://www.ubht.nhs.uk/press/view.asp?257 announced a randomised trial for homeopathic treatment of asthma in children. This was reported also on the BBC http://news.bbc.co.uk/1/hi/england/bristol/4971050.stm . I’d be very grateful if you could let me know when results from this trial will become available. Yours sincerely David Colquhoun |
The reply, dated 11 December 2007, was unsympathetic
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I have just submitted the funders report today and we have set ourselves the deadline to publish two inter-related papers by March 1st 2007. Can I ask why you are asking and what authority you have to gain this information. I shall expect a reply to my questions, |
I answered this question politely on the same day but nevertheless my innocent enquiry drew forth a rather vitriolic complaint from Dr Thompson to the Provost of UCL (dated 14 December 2007). In this case, the Provost came up trumps. On 14 January 2008 he replied to Thompson: “I have looked at the email that you copied to me, and I must say that it seems an entirely proper and reasonable request. It is not clear to me why Professor Colquhoun should require some special authority to make such direct enquiries”. Dr Thompson seems to be very sensitive. We have yet to see the results of her trial in which I’m still interested.
Not surprisingly, Dr Dixon has had some severe criticism for his views, not least from the UK’s foremost expert on the evidence for efficacy, Prof Edzard Ernst. Accounts of this can be found in Pulse,
and on Andrew Lewis’s blog.
Dixon is now (in)famous in the USA too. The excellent Yale neurologist, Steven Novella, has written an analysis of his views on Science Based Medicine. He describes Dr. Michael Dixon as “A Pyromaniac In a Field of (Integrative) Straw Men”
Peter Hain
09:40 Politics and people: can integrated health and care take centre stage in 2009/2010? Rt Hon Peter Hain MP
It seems that Peter Hain was converted to alternative medicine when his first baby, Sam, was born with eczema. After (though possibly not because of) homeopathic treatment and a change in diet, the eczema got better. This caused Hain, while Northern Ireland Secretary to spend £200,000 of taxpayers’ money to set up a totally uninformative customer satisfaction survey, which is being touted elsewhere in this meeting as though it were evidence (see below). I have written about this episode before: see Peter Hain and Get Well UK: pseudoscience and privatisation in Northern Ireland.
I find it very sad that a hero of my youth (for his work in the anti-apartheid movement) should have sunk to promoting junk science, and even sadder that he does so at my expense.
There has been a report on Hain’s contribution in Wales Online.
09:55 Why does the Health Service need a new perspective on health and healing? Sir Cyril Chantler, Chair, King’s Fund, previous Dean, Guy’s Hospital and Great Ormond Street
Cyril Chantler is a distinguished medical administrator. He also likes to talk and we have discussed the quackery problem several times. He kindly sent me the slides that he used. Slide 18 says that in order to do some good we “need to demonstrate that the treatment is clinically effective and cost effective for NHS use”. That’s impeccable, but throughout the rest of the slides he talks of integrating with complementary” therapies, the effectiveness of which is either already disproved or simply not known.
I remain utterly baffled by the reluctance of some quite sensible people to grasp the nettle of deciding what works. Chantler fails to grasp the nettle, as does the Department of Health. Until they do so, I don’t see how they can be taken seriously.
10.05 Panel discussion
The Awards
10:20 Integrated Health Awards 2009 Introduction: a review of the short-listed applications
10:45 Presentations to the Award winners by the special guest speaker
11:00 Keynote address by special guest speaker
Getting integrated
Dr David Peters
12:00 Integration, long term disease and creating a sustainable NHS. Professor David Peters, Clinical Director and Professor of Integrated Healthcare, University of Westminster
I first met David Peters after Nature ran my article, Science Degrees without the Science. .One of the many media follow-ups of that article was on Material World (BBC Radio 4). This excellent science programme, presented by Quentin Cooper, had a discussion between me and David Peters ( listen to the mp3 file).
There was helpful intervention from Michael Marmot who had talked, in the first half of the programme, about his longitudinal population studies.
Marmot stressed the need for proper testing. In the case of
homeopathy and acupuncture, that proper testing has largely been done. The tests were failed.
The University of Westminster has, of course, gained considerable notoriety as the university that runs more degree programmes in anti-scientific forms of medicine than any other. Their lecture on vibrational medicine teaches students that amethysts “emit high Yin energy so transmuting lower energies and clearing and aligning energy disturbances at all levels of being”. So far their vice-chancellor, Professor Geoffrey Petts, has declined to answer enquiries about whether he thinks such gobbledygook is appropriate for a BSc degree.
But he did set up an internal enquiry into the future of their alternative activities. Sadly that enquiry seems to have come to the nonsensical conclusion that the problem can be solved by injection of good science into the courses, as reported here and in the Guardian.
It seems obvious that if you inject good science into their BSc in homeopathy the subject will simply vanish in a puff of smoke.
In 2007, the University of Westminster did respond to earlier criticism in Times Higher Education, but their response seemed to me to serve only to dig themselves deeper into a hole.
Nevertheless, Westminster has now closed down its homeopathy degree (the last in the country to go) and there is intense internal discussion going on there. I have the impression that Dr Peters’ job is in danger. The revelation of more slides from their courses on homeopathy, naturopathy and Chinese herbal medicine shows that these courses are not only barmy, but also sometimes dangerous.
Professor Chris Fowler
12:10 Educating tomorrow’s integrated doctors. Professor Chris Fowler, Dean for Education, Barts and The London School of Medicine and Dentistry
I first came across Dr Fowler when I noticed him being praised for his teaching of alternative medicine to students at Barts and the London Medical School on the web site of the Prince’s Foundation. I wrote him a polite letter to ask if he really thought that the Prince of Wales was the right person to consult about the education of medical students. The response I got was, ahem, unsympathetic. But a little while later I noticed that two different Barts students had set up public blogs that criticised strongly the nonsense that was being inflicted on them.
At that point, I felt it was necessary to support the students who, it seemed to me, knew more about medical education than Professor Fowler. It didn’t take long to uncover the nonsense that was being inflicted on the students: read about it here.
There is a follow-up to this story here. Fortunately, Barts’ Director of Research, and, I’m told, the Warden of Barts, appear to agree with my view of the harm that this sort of thing can do to the reputation of Barts, so things may change soon,
Dame Donna Kinnair
12:30 Educating tomorrow’s integrated nurses.
Dame Donna Kinnair, Director of Nursing, Southwark PCT
As far as I can see, Donna Kinnair has no interest in alternative medicine. She is director of nursing at Southwark primary care trust and was an adviser to Lord Laming throughout his inquiry into the death of Victoria Climbié. I suspect that her interest is in integrating child care services (they need it, judging by the recent death of ‘Baby P’). Perhaps her presence shows the danger of using euphemisms like ‘integrated medicine’ when what you really mean is the introduction of unproven or disproved forms of medicine.
Michael Dooley
12:40 Integrating the care of women: an example of the new paradigm. Michael Dooley, Consultant Obstetrician and Gynecologist
DC’s rule 2. Never trust anyone who uses the word ‘paradigm’. It is a sure-fire sign of pseudoscience. In this case, the ‘new paradigm’ seems to be the introduction of disproven treatment. Dooley is a gynaecologist and Medical Director of the Poundbury Clinic. His clinic offers a whole range of unproven and disproved treatments. These include acupuncture as an aid to conception in IVF. This is not recommended by the Cochrane review, and one report suggests that it hinders conception rather than helps.
12.40 Discussion
13.00 – 14.00 Lunch and Exhibition
15.30 Tea
Boo Armstrong and Get Well UK
16.00 Integrated services in action: The Northern
Ireland experience: what has it shown us and what are its implications?
Boo Armstrong of Get Well UK with a team from the NI study
I expect that much will be made of this “study”, which, of course, tells you absolutely nothing whatsoever about the effectiveness of the alternative treatments that were used in it. This does not appear to be the view of Boo Armstrong, On the basis of the “study”, her company’s web site proclaims boldly
“Complementary Medicine Works
Get Well UK ran the first government-backed complementary therapy project in the UK, from February 2007 to February 2008″
This claim appears, prima facie, to breach the Unfair Trading Regulations of May 2008. The legality of the claim is, at the moment, being judged by a Trading Standards Officer. In any case, the “study” was not backed by the government as a whole, but just by Peter Hain’s office. It is not even clear that it had ethical approval.
The study consisted merely of asking people who had seen an alternative medicine practitioner whether they felt better or worse. There was no control group; no sort of comparison was made. It is surely obvious to the most naive person that a study like this cannot even tell you if the treatment has a placebo effect, never mind that it has any genuine effects of its own. To claim that it does so seems to be simply dishonest. There is no reason at all to think that the patients would not have got better anyway.
It is not only Get Well UK who misrepresent the evidence. The Prince’s
Foundation itself says
“Now a new, year long trial supported by the Northern Ireland health service has . . . demonstrated that integrating complementary and conventional medicine brings measurable benefits to patients’ health.”
That is simply not true. It is either dishonest or stupid. Don’t ask me which, I have no idea.
This study is no more informative than the infamous Spence (2005) ‘study’ of the same type, which seems to be the only thing that homeopaths can produce to support their case.
There is an excellent analysis of the Northern Ireland ‘study’ by Andy Lewis, The Northern Ireland NHS Alternative Medicine ‘Trial’. He explains patiently, yet again, what constitutes evidence and why studies like this are useless.
His analogy starts
” . . . the Apple Marketing Board approach the NHS and ask for £200,000 to do a study to show the truth behind the statement ‘An apple a day keeps the doctor away’. The Minister, being particularly fond of apples, agrees and the study begins.”
16.30 Social enterprise and whole systems integrated care. Dee Kyne, Sandwell PCT and a GP. Developing an integrated service in secondary care
Dee Kyne appears to be CEO of KeepmWell Ltd (a financial interest that is not mentioned).
Peter Mackereth, Clinical Lead, Supportive Services, Christie Hospital NHS Foundation Trust
I had some correspondence with Mackereth when the Times (7 Feb 2007) published a picture of the Prince of Wales inspecting an “anti-MRSA aromatherapy inhaler” in his department at the Christie. It turned out that the trial they were doing was not blind No result has been announced anyway, and on enquiry, I find that the trial has not even started yet. Surprising, then to find that the FIH is running the First Clinical Aromatherapy Conference at the Christie Hospital, What will there be to talk about?
Much of what they do at the Christie is straightforward massage, but they also promote the nonsensical principles of “reflexology” and acupuncture.
The former is untested. The latter is disproven.
Parallel Sessions
Developing a PCT funded musculoskeletal service Dr Roy Welford, Glastonbury Health Centre
Roy Welford is a Fellow of the Faculty of Homeopathy, and so promotes disproven therapies. The Glastonbury practice also advertises acupuncture (disproven), osteopathy and herbal medicine (largely untested so most of it consists of giving patients an unknown dose of an ill-defined drug, of unknown effectiveness and unknown safety).
Making the best of herbal self-prescription in integrated practice: key remedies and principles. Simon Mills, Project Lead: Integrated Self Care in Family Practice, Culm Valley Integrated Centre for Health, Devon
Simon Mills is a herbalist who now describes himself as a “phytotherapist” (it sounds posher, but the evidence, or lack of it, is not changed by the fancy name). Mills likes to say things like “there are herbs for heating and drying”, “hot and cold” remedies, and to use meaningless terms like “blood cleanser”, but he appears to be immune to the need for good evidence that herbs work before you give them to sick people. He says, at the end of a talk, “The hot and the cold remain the trade secret of traditional medicine”. And this is the 21st Century.
Practical ways in which complementary approaches can improve the treatment of cancer. Professor Jane Plant, Author of “Your life in your hands” and Chief Scientist, British Geological Society and Professor Karol Sikora, Medical Director, Cancer Partners UK
Jane Plant is a geologist who, through her own unfortunate encounter with breast cancer, became obsessed with the idea that a dairy-free diet cured her. Sadly there is no good evidence for that idea, according to the World Cancer Research Fund Report, led by Professor Sir Michael Marmot. No doubt her book on the subject sells well, but it could be held that it is irresponsible to hold out false hopes to desperate people. She is a supporter of the very dubious CancerActive organisation (also supported by Michael Dixon OBE –see above) as well as the notorious pill salesman, Patrick Holford (see also here).
Karol Sikora, formerly an oncologist at the Hammersmith Hospital, is now Dean of Medicine at the University of Buckingham (the UK’s only private university). He is also medical director at CancerPartners UK, a private cancer company.
He recently shot to fame when he appeared in a commercial in the USA sponsored by “Conservatives for Patients’ Rights”, to pour scorn on the NHS, and to act as an advocate for the USA’s present health system. A very curious performance. Very curious indeed.
His attitude to quackery is a mystery wrapped in an enigma. One was somewhat alarmed to see him sponsoring a course at what was, at first, called the British College of Integrated Medicine, and has now been renamed the Faculty of Integrated Medicine That grand title makes it sound like part of a university. It isn’t.
The alarm was as result of the alliance with Dr Rosy Daniel (who promotes an untested herbal conconction, Carctol, for ‘healing’ cancer) and Dr Mark Atkinson (a supplement salesman who has also promoted the Qlink pendant. The Qlink pendant is a simple and obvious fraud designed to exploit paranoia about WiFi killing you.
The first list of speakers on the proposed diploma in Integrated Medicine was an unholy alliance of outright quacks and commercial interests. It turned out that, although Karol Sikora is sponsoring the course, he knew nothing about the speakers. I did and when I pointed this out to Terence Kealey, vice-chancellor of Buckingham, he immediately removed Rosy Daniel from directing the Diploma. At the moment the course is being revamped entirely by Andrew Miles. There is hope that he’ll do a better job. It has not yet been validated by the University of Buckingham. Watch this space for developments.
Stop press It is reported in the Guardian that Professor Sikora has been describing his previous job at Imperial College with less than perfect accuracy. Oh dear. More developments in the follow-up.
The role of happy chickens in healing: farms as producers of health as well as food – the Care Farm Initiative Jonathan Dover, Project Manager, Care Farming, West Midlands.
“Care farming is a partnership between farmers, participants and health & social care providers. It combines the care of the land with the care of people, reconnecting people with nature and their communities.”
Sounds lovely, I wonder how well it works?
What can the Brits learn from the Yanks when it comes to integrated health? Jack Lord, Chief Executive Humana Europe
It is worth noticing that the advisory board of Humana Europe includes Micheal Dixon OBE, a well known advocate of alternative medicine (see
above). Humana Europe is a private company, a wholly owned subsidiary of Humana Inc., a health benefits company with 11 million members and 22,000 employees and headquarters in Louisville, Kentucky. In 2005 it entered into a business partnership with Virgin Group. Humana was mentioned in the BBC Panorama programme “NHS for Sale”. The company later asked that it be pointed out that they provide commissioning services, not clinical services [Ed. well not yet anyway].
Humana’s document “Humana uses computer games to help people lead healthier lives” is decidedly bizarre. Hang on, it was only a moment ago that we were being told that computer games rewired your brain.
Day 2 Integrated health in action
09.00 Health, epidemics and the search for new solutions. Sir Michael Marmot, Professor of Epidemiology and Public Health, Royal Free and University College Medical School
It is a mystery to me that a distinguished epidemiologist should be willing to keep such dubious company. Sadly I don’t know what he said, but judging my his publications and his appearence on Natural World, I can’t imagine he’d have much time for homeopaths.
9.25 Improving health in the workplace. Dame Carol Black, National Director, Health and Work, Department of Health
This is not the first time that Dame Carol has been comtroversial.
9.45 Integrated health in focus: defeating obesity. Professor Chris Drinkwater, President, NHS Alliance.
The NHS Alliance was mentioned above. Enough said.
10.00 Integrated healthcare in focus: new approaches to managing asthma, eczema and allergy. Professor Stephen Holgate, Professor of Immunopharmacology, University of Southampton
10.15 Using the natural environment to increase activity. The Natural England Project: the results from year one. Dr William Bird and Ruth Tucker, Natural England.
10.30 Panel discussion
10.45 Coffee
Self help in action
11.10 Your health, your way: supporting self care through care planning and the use of personal budgets. Angela Hawley, Self Care Lead, Department of Health
11.25 NHS Life Check: providing the signposts to
integrated health. Roy Lambley, Project Director, NHS LifeCheck Programme
This programme was developed with the University of Westminster’s “Health and Well-being Network”. This group, with one exception, is separate from Westminster’s extensive alternative medicine branch (it’s mostly psychologists).
11.45 The agony and the ecstasy of helping patients to help themselves: tips for clinicians, practices and PCTs. Professor
Ruth Chambers, FIH Foundation Fellow.
11.55 Providing self help in practice: Department of Health Integrated Self Help Information Project. Simon Mills, Project Lead: Integrated Self Care in Family Practice, Culm Valley Integrated Centre for Health, Devon and Dr Sam Everington, GP, Bromley by Bow.
The Culm Valley Integrated Centre for health is part of the College Surgery Partnership, associated with Michael Dixon OBE (yes, again!).
Simon Mills is the herbalist who says “The hot and the cold remain the trade secret of traditional medicine” .
Sam Everington, in contrast, seems to be interested in ‘integration’ in the real sense of the word, rather than quackery.
Integrated health in action
How to make sense of the evidence on complementary approaches: what works? What might work? What doesn’t work?
Dr Hugh MacPherson, Senior Research Fellow in Health Sciences, York University and Dr Catherine Zollman, Bravewell Fellow
Hugh MacPherson‘s main interest is in acupuncture and he publishes in alternative medicine journals. Since the recent analysis in the BMJ from the Nordic Cochrane Centre (Madsen et al., 2009) it seems that acupuncture is finally dead. Even its placebo effect is too small to be useful. Catherine Zollman is a Bristol GP who is into homeopathy as well as acupuncture. She is closely connected with the Prince’s Foundation via the Bravewell Fellowship. That fellowship is funded by the Bravewell Collaboration, which is run by Christie Mack, wife of John Mack (‘Mack the Knife’), head of Morgan Stanley (amazingly, they still seem to have money). This is the group which, by sheer wealth, has persuaded so many otherwise respectable US universities to embrace every sort of quackery (see, for example, Integrative baloney @ Yale)
The funding of integrated services
14.15 How to get a PCT or practice- based commissioner to fund your integrated service. A PCT Chief Executive and a Practice-Based Commissioning lead.
14.30 How I succeeded: funding an integrated service. Dr John Ribchester, Whitstable
14.45 How we created an acupuncture service in St Albans and Harpenden PBC group. Mo Girach, Chief Executive, STAHCOM
Uhuh Acupunture again. Have these people never read Bausell’s
book? Have they not read the BMJ? Acupuncture is now ell-established to be based on fraudulent principles, and not even to have a worthwhile placeobo effect. STAHCOM seem to be more interested in money than in what works.
Dragon’s Den. Four pitchers lay out their stall for the commissioning dragons
And at this stage there is no prize for guessing that all four are devoted to trying to get funds for discredited treatments
- An acupuncture service for long-term pain. Mike Cummings Chair, Medical Acupuncture Association
- Manipulation for the treatment of back pain Simon Fielding, Founder Chairman of the General Osteopathic Council
- Nigel Clarke, Senior Partner, Learned Lion Partners Homeopathy for long term conditions
- Peter Fisher, Director, Royal Homeopathic Hospital
Sadly it is not stated who the dragons are. One hopes they will be more interested in evidence than the supplicants.
Mike Cummings at least doesn’t believe the nonsense about meridians and Qi. It’s a pity he doesn’t look at the real evidence though.
You can read something about him and his journal at BMJ Group promotes acupuncture: pure greed.
Osteopathy sounds a bit more respectable than the others, but in fact it has never shaken off its cult-like origins. Still many osteopaths make absurd claims to cure all sorts of diseases. Offshoots of osteopathy like ‘cranial osteopathy’ are obvious nonsense. There is no reason to think that osteopathy is any better than any other manipulative therapy and it is clear that all manipulative therapies should be grouped into one.
Osteopathy and chiropractic provide the best ever examples of the folly of giving official government recognition to a branch of alternative medicine before the evidence is in.
Learned Lion Partners is a new one on me. It seems it is
part of Madsen Gornall Ashe Chambers (‘MGA Chambers’) “a grouping of top level, independent specialists who provide a broad range of management consultancy advice to the marketing community”. It’s a management consultant and marketing outfit. So don’t expect too much when it comes to truth and evidence. The company web site says nothing about alternative medicine, but only that Nigel Clarke
“. . . has very wide experience of public affairs issues and campaigns, having worked with clients in many sectors in Europe, North America and the Far East. He has particular expertise in financial, competition and healthcare issues. “
However, all is revealed when we see that he is a Trustee of the Prince’s Foundation where his entry says
“Nigel Clarke is senior partner of Learned Lion Partners. He is a director of Vidapulse Ltd, Really Easy Ltd, Newscounter Ltd and Advanced Transport Systems Ltd. He has worked on the interfaces of public policy for 25 years. He has been chair of the General Osteopathic Council since May 2001, having been a lay member since it was formed. He is now a member of the Council for Healthcare Regulatory Excellence”
The Council for Healthcare Regulatory Excellence is yet another quango that ticks boxes and fails absolutely to grasp the one important point, does it work?. I came across them at the Westminster Forum, and they seemed a pretty pathetic way to spend £2m per year.
Peter Fisher is the last supplicant to the Dragons. He is clinical director of the Royal London Homeopathic Hospital (RLHH), and Queen’s homeopathic physician, It was through him that I got an active interest in quackery. The TV programme QED asked me to check the statistics in a paper of his that claimed that homeopathy was good for fibrositis (there was an elementary mistake and no evidence for an effect). Peter Fisher is also remarkable because he agreed with me that BSc degrees in homeopathy were not justified (on TV –see the movie). And he condemned homeopaths who were caught out recommending their sugar pills for malaria. To that extent Fisher represents the saner end of the homeopathic spectrum. Nevertheless he still maintains that sugar pills work and have effects of their own, and tries to justify the ‘memory of water’ by making analogies with a memory stick or CD. This is so obviously silly that no more comment is needed.
Given Fisher’s sensible condemnation of the malaria fiasco, I was rather surprised to see that he appeared on the programme of a conference at the University of Middlesex, talking about “A Strategy To Research The Potential Of Homeopathy In Pandemic Flu”. The title of the conference was Developing Research Strategies in CAM. A colleague, after seeing the programme, thought it was more like “a right tossers’ ball”.
Much of the homeopathy has now vanished from the RLHH as a result of greatly reduced commissioning by PCTs (read about it in Fisher’s own words). And the last homeopathy degree in the UK has closed down. It seems an odd moment for the FIH to be pushing it so hard.
Follow-up
Stop press It is reported in the Guardian (22 May 2009) that Professor Sikora has been describing his previous job at Imperial College with less than perfect accuracy. Oh dear, oh dear.
This fascinating fact seems to have been unearthed first by the admirable NHS Blog Doctor, in his post ‘Imperial College confirm that Karol Sikora does not work for them and does not speak on their behalf‘.
This article has been reposted on The Winnower, and now has a digital object identifier DOI: 10.15200/winn.142934.47856
This post is not about quackery, nor university politics. It is about inference, How do we know what we should eat? The question interests everyone, but what do we actually know? Not as much as you might think from the number of column-inches devoted to the topic. The discussion below is a synopsis of parts of an article called “In praise of randomisation”, written as a contribution to a forthcoming book, Evidence, Inference and Enquiry.
About a year ago just about every newspaper carried a story much like this one in the Daily Telegraph,
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Sausage a day can increase bowel cancer risk By Rebecca Smith, Medical Editor Last Updated: 1:55AM BST 31/03/2008
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What, I wondered, was the evidence behind these dire warnings. They did not come from a lifestyle guru, a diet faddist or a supplement salesman. This is nothing to do with quackery. The numbers come from the 2007 report of the World Cancer Research Fund and American Institute for Cancer Research, with the title ‘Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective‘. This is a 537 page report with over 4,400 references. Its panel was chaired by Professor Sir Michael Marmot, UCL’s professor of Epidemiology and Public Health. He is a distinguished epidemiologist, renowned for his work on the relation between poverty and health.
Nevertheless there has never been a randomised trial to test the carcinogenicity of bacon, so it seems reasonable to ask how strong is the evidence that you shouldn’t eat it? It turns out to be surprisingly flimsy.
In praise of randomisation
Everyone knows about the problem of causality in principle. Post hoc ergo propter hoc; confusion of sequence and consequence; confusion of correlation and cause. This is not a trivial problem. It is probably the main reason why ineffective treatments often appear to work. It is traded on by the vast and unscrupulous alternative medicine industry. It is, very probably, the reason why we are bombarded every day with conflicting advice on what to eat. This is a bad thing, for two reasons. First, we end up confused about what we should eat. But worse still, the conflicting nature of the advice gives science as a whole a bad reputation. Every time a white-coated scientist appears in the media to tell us that a glass of wine per day is good/bad for us (delete according to the phase of the moon) the general public just laugh.
In the case of sausages and bacon, suppose that there is a correlation between eating them and developing colorectal cancer. How do we know that it was eating the bacon that caused the cancer – that the relationship is causal? The answer is that there is no way to be sure if we have simply observed the association. It could always be that the sort of people who eat bacon are also the sort of people who get colorectal cancer. But the question of causality is absolutely crucial, because if it is not causal, then stopping eating bacon won’t reduce your risk of cancer. The recommendation to avoid all processed meat in the WCRF report (2007) is sensible only if the relationship is causal. Barker Bausell said:
[Page39] “But why should nonscientists care one iota about something as esoteric as causal inference? I believe that the answer to this question is because the making of causal inferences is part of our job description as Homo Sapiens.”
That should be the mantra of every health journalist, and every newspaper reader.
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The essential basis for causal inference was established over 70 years ago by that giant of statistics Ronald Fisher, and that basis is randomisation. Its first popular exposition was in Fisher’s famous book, The Design of Experiments (1935). The Lady Tasting Tea has become the classical example of how to design an experiment. . |
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Briefly, a lady claims to be able to tell whether the milk was put in the cup before or after the tea was poured. Fisher points out that to test this you need to present the lady with an equal number of cups that are ‘milk first’ or ‘tea first’ (but otherwise indistinguishable) in random order, and count how many she gets right. There is a beautiful analysis of it in Stephen Senn’s book, Dicing with Death: Chance, Risk and Health. As it happens, Google books has the whole of the relevant section Fisher’s tea test (geddit?), but buy the book anyway. Such is the fame of this example that it was used as the title of a book, The Lady Tasting Tea was published by David Salsburg (my review of it is here)
Most studies of diet and health fall into one of three types, case-control studies, cohort (or prospective) studies, or randomised controlled trials (RCTs). Case-control studies are the least satisfactory: they look at people who already have the disease and look back to see how they differ from similar people who don’t have the disease. They are retrospective. Cohort studies are better because they are prospective: a large group of people is followed for a long period and their health and diet is recorded and later their disease and death is recorded. But in both sorts of studies,each person decides for him/herself what to eat or what drugs to take. Such studies can never demonstrate causality, though if the effect is really big (like cigarette-smoking and lung cancer) they can give a very good indication. The difference in an RCT is that each person does not choose what to eat, but their diet is allocated randomly to them by someone else. This means that, on average, all other factors that might influence the response are balanced equally between the two groups. Only RCTs can demonstrate causality.
Randomisation is a rather beautiful idea. It allows one to remove, in a statistical sense, bias that might result from all the sources that you hadn’t realised were there. If you are aware of a source of bias, then measure it. The danger arises from the things you don’t know about, or can’t measure (Senn, 2004; Senn, 2003). Although it guarantees freedom from bias only in a long run statistical sense, that is the best that can be done. Everything else is worse.
Ben Goldacre has referred memorably to the newspapers’ ongoing “Sisyphean task of dividing all the inanimate objects in the world into the ones that either cause or cure cancer” (Goldacre, 2008). This has even given rise to a blog. “The Daily Mail Oncological Ontology Project“. The problem arises in assessing causality.
It wouldn’t be so bad if the problem were restricted to the media. It is much more worrying that the problem of establishing causality often seems to be underestimated by the authors of papers themselves. It is a matter of speculation why this happens. Part of the reason is, no doubt, a genuine wish to discover something that will benefit mankind. But it is hard not to think that hubris and self-promotion may also play a role. Anything whatsoever that purports to relate diet to health is guaranteed to get uncritical newspaper headlines.
At the heart of the problem lies the great difficulty in doing randomised studies of the effect of diet and health. There can be no better illustration of the vital importance of randomisation than in this field. And, notwithstanding the generally uncritical reporting of stories about diet and health, one of the best accounts of the need for randomisation was written by a journalist, Gary Taubes, and it appeared in the New York Times (Taubes, 2007).
The case of hormone replacement therapy
In the 1990s hormone replacement therapy (HRT) was recommended not only to relieve the unpleasant symptoms of the menopause, but also because cohort studies suggested that HRT would reduce heart disease and osteoporosis in older women. For these reasons, by 2001, 15 million US women (perhaps 5 million older women) were taking HRT (Taubes, 2007). These recommendations were based largely on the Harvard Nurses’ Study. This was a prospective cohort study in which 122,000 nurses were followed over time, starting in 1976 (these are the ones who responded out of the 170,000 requests sent out). In 1994, it was said (Manson, 1994) that nearly all of the more than 30 observational studies suggested a reduced risk of coronary heart disease (CHD) among women receiving oestrogen therapy. A meta-analysis gave an estimated 44% reduction of CHD. Although warnings were given about the lack of randomised studies, the results were nevertheless acted upon as though they were true. But they were wrong. When proper randomised studies were done, not only did it turn out that CHD was not reduced: it was actually increased.
The Women’s Health Initiative Study (Rossouw et al., 2002) was a randomized double blind trial on 16,608 postmenopausal women aged 50-79 years and its results contradicted the conclusions from all the earlier cohort studies. HRT increased risks of heart disease, stroke, blood clots, breast cancer (though possibly helped with osteoporosis and perhaps colorectal cancer). After an average 5.2 years of follow-up, the trial was stopped because of the apparent increase in breast cancer in the HRT group. The relative risk (HRT relative to placebo) of CHD was 1.29 (95% confidence interval 1.02 to 1.63) (286 cases altogether) and for breast cancer 1.26 (1.00 -1.59) (290 cases). Rather than there being a 44% reduction of risk, it seems that there was actually a 30% increase in risk. Notice that these are actually quite small risks, and on the margin of statistical significance. For the purposes of communicating the nature of the risk to an individual person it is usually better to specify the absolute risk rather than relative risk. The absolute number of CHD cases per 10,000 person-years is about 29 on placebo and 36 on HRT, so the increased risk of any individual is quite small. Multiplied over the whole population though, the number is no longer small.
Several plausible reasons for these contradictory results are discussed by Taubes,(2007): it seems that women who choose to take HRT are healthier than those who don’t. In fact the story has become a bit more complicated since then: the effect of HRT depends on when it is started and on how long it is taken (Vandenbroucke, 2009).
This is perhaps one of the most dramatic illustrations of the value of randomised controlled trials (RCTs). Reliance on observations of correlations suggested a 44% reduction in CHD, the randomised trial gave a 30% increase in CHD. Insistence on randomisation is not just pedantry. It is essential if you want to get the right answer.
Having dealt with the cautionary tale of HRT, we can now get back to the ‘Sisyphean task of dividing all the inanimate objects in the world into the ones that either cause or cure cancer’.
The case of processed meat
The WCRF report (2007) makes some pretty firm recommendations.
- Don’t get overweight
- Be moderately physically active, equivalent to brisk walking for at least 30 minutes every day
- Consume energy-dense foods sparingly. Avoid sugary drinks. Consume ‘fast foods’ sparingly, if at all
- Eat at least five portions/servings (at least 400 g or 14 oz) of a variety of non-starchy vegetables and of fruits every day. Eat relatively unprocessed cereals (grains) and/or pulses (legumes) with every meal. Limit refined starchy foods
- People who eat red meat to consume less than 500 g (18 oz) a week, very little if any to be processed.
- If alcoholic drinks are consumed, limit consumption to no more than two drinks a day for men and one drink a day for women.
- Avoid salt-preserved, salted, or salty foods; preserve foods without using salt. Limit consumption of processed foods with added salt to ensure an intake of less than 6 g (2.4 g sodium) a day.
- Dietary supplements are not recommended for cancer prevention.
These all sound pretty sensible but they are very prescriptive. And of course the recommendations make sense only insofar as the various dietary factors cause cancer. If the association is not causal, changing your diet won’t help. Note that dietary supplements are NOT recommended. I’ll concentrate on the evidence that lies behind “People who . . . very little if any to be processed.”
The problem of establishing causality is dicussed in the report in detail. In section 3.4 the report says
” . . . causal relationships between food and nutrition, and physical activity can be confidently inferred when epidemiological evidence, and experimental and other biological findings, are consistent, unbiased, strong, graded, coherent, repeated, and plausible.”
The case of processed meat is dealt with in chapter 4.3 (p. 148) of the report.
“Processed meats” include sausages and frankfurters, and ‘hot dogs’, to which nitrates/nitrites or other preservatives are added, are also processed meats. Minced meats sometimes, but not always, fall inside this definition if they are preserved chemically. The same point applies to ‘hamburgers’.
The evidence for harmfulness of processed meat was described as “convincing”, and this is the highest level of confidence in the report, though this conclusion has been challenged (Truswell, 2009) .
How well does the evidence obey the criteria for the relationship being causal?
Twelve prospective cohort studies showed increased risk for the highest intake group when compared to the lowest, though this was statistically significant in only three of them. One study reported non-significant decreased risk and one study reported that there was no effect on risk. These results are summarised in this forest plot (see also Lewis & Clark, 2001)
Each line represents a separate study. The size of the square represents the precision (weight) for each. The horizontal bars show the 95% confidence intervals. If it were possible to repeat the observations many times on the same population, the 95% CL would be different on each repeat experiment, but 19 out of 20 (95%) of the intervals would contain the true value (and 1 in 20 would not contain the true value). If the bar does not overlap the vertical line at relative risk = 1 (i.e. no effect) this is equivalent to saying that there is a statistically significant difference from 1 with P < 0.05. That means, very roughly, that there is a 1 in 20 chance of making a fool of yourself if you claim that the association is real, rather than being a result of chance (more detail here),
There is certainly a tendency for the relative risks to be above one, though not by much, Pooling the results sounds like a good idea. The method for doing this is called meta-analysis .
Meta-analysis was possible on five studies, shown below. The outcome is shown by the red diamond at the bottom, labelled “summary effect”, and the width of the diamond indicates the 95% confidence interval. In this case the final result for association between processed meat intake and colorectal cancer was a relative risk of 1.21 (95% CI 1.04–1.42) per 50 g/day. This is presumably where the headline value of a 20% increase in risk came from.
Support came from a meta-analysis of 14 cohort studies, which reported a relative risk for processed meat of 1.09 (95% CI 1.05 – 1.13) per 30 g/day (Larsson & Wolk, 2006). Since then another study has come up with similar numbers (Sinha etal. , 2009). This consistency suggests a real association, but it cannot be taken as evidence for causality. Observational studies on HRT were just as consistent, but they were wrong.
The accompanying editorial (Popkin, 2009) points out that there are rather more important reasons to limit meat consumption, like the environmental footprint of most meat production, water supply, deforestation and so on.
So the outcome from vast numbers of observations is an association that only just reaches the P = 0.05 level of statistical significance. But even if the association is real, not a result of chance sampling error, that doesn’t help in the least in establishing causality.
There are two more criteria that might help, a good relationship between dose and response, and a plausible mechanism.
Dose – response relationship
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It is quite possible to observe a very convincing relationship between dose and response in epidemiological studies, The relationship between number of cigarettes smoked per day and the incidence of lung cancer is one example. Indeed it is almost the only example. |
 Doll & Peto, 1978 |
There have been six studies that relate consumption of processed meat to incidence of colorectal cancer. All six dose-response relationships are shown in the WCRG report. Here they are.
This Figure was later revised to
This is the point where my credulity begins to get strained. Dose – response curves are part of the stock in trade of pharmacologists. The technical description of these six curves is, roughly, ‘bloody horizontal’. The report says “A dose-response relationship was also apparent from cohort studies that measured consumption in times/day”. I simply cannot agree that any relationship whatsoever is “apparent”.
They are certainly the least convincing dose-response relationships I have ever seen. Nevertheless a meta-analysis came up with a slope for response curve that just reached the 5% level of statistical significance.
The conclusion of the report for processed meat and colorectal cancer was as follows.
“There is a substantial amount of evidence, with a dose-response relationship apparent from cohort studies. There is strong evidence for plausible mechanisms operating in humans. Processed meat is a convincing cause of colorectal cancer.”
But the dose-response curves look appalling, and it is reasonable to ask whether public policy should be based on a 1 in 20 chance of being quite wrong (1 in 20 at best –see Senn, 2008). I certainly wouldn’t want to risk my reputation on odds like that, never mind use it as a basis for public policy.
So we are left with plausibility as the remaining bit of evidence for causality. Anyone who has done much experimental work knows that it is possible to dream up a plausible explanation of any result whatsoever. Most are wrong and so plausibility is a pretty weak argument. Much play is made of the fact that cured meats contain nitrates and nitrites, but there is no real evidence that the amount they contain is harmful.
The main source of nitrates in the diet is not from meat but from vegetables (especially green leafy vegetables like lettuce and spinach) which contribute 70 – 90% of total intake. The maximum legal content in processed meat is 10 – 25 mg/100g, but lettuce contains around 100 – 400 mg/100g with a legal limit of 200 – 400 mg/100g. Dietary nitrate intake was not associated with risk for colorectal cancer in two cohort studies.(Food Standards Agency, 2004; International Agency for Research on Cancer, 2006).
To add further to the confusion, another cohort study on over 60,000 people compared vegetarians and meat-eaters. Mortality from circulatory diseases and mortality from all causes were not detectably different between vegetarians and meat eaters (Key et al., 2009a). Still more confusingly, although the incidence of all cancers combined was lower among vegetarians than among meat eaters, the exception was colorectal cancer which had a higher incidence in vegetarians than in meat eaters (Key et al., 2009b).
Mente et al. (2009) compared cohort studies and RCTs for effects of diet on risk of coronary heart disease. “Strong evidence” for protective effects was found for intake of vegetables, nuts, and “Mediterranean diet”, and harmful effects of intake of trans–fatty acids and foods with a high glycaemic index. There was also a bit less strong evidence for effects of mono-unsaturated fatty acids and for intake of fish, marine ω-3 fatty acids, folate, whole grains, dietary vitamins E and C, beta carotene, alcohol, fruit, and fibre. But RCTs showed evidence only for “Mediterranean diet”, and for none of the others.
As a final nail in the coffin of case control studies, consider pizza. According to La Vecchia & Bosetti (2006), data from a series of case control studies in northern Italy lead to: “An inverse association was found between regular pizza consumption (at least one portion of pizza per week) and the risk of cancers of the digestive tract, with relative risks of 0.66 for oral and pharyngeal cancers, 0.41 for oesophageal, 0.82 for laryngeal, 0.74 for colon and 0.93 for rectal cancers.”
What on earth is one meant to make of this? Pizza should be prescribable on the National Health Service to produce a 60% reduction in oesophageal cancer? As the authors say “pizza may simply represent a general and aspecific indicator of a favourable Mediterranean diet.” It is observations like this that seem to make a mockery of making causal inferences from non-randomised studies. They are simply uninterpretable.
Is the observed association even real?
The most noticeable thing about the effects of red meat and processed meat is not only that they are small but also that they only just reach the 5 percent level of statistical significance. It has been explained clearly why, in these circumstances, real associations are likely to be exaggerated in size (Ioannidis, 2008a; Ioannidis, 2008b; Senn, 2008). Worse still, there as some good reasons to think that many (perhaps even most) of the effects that are claimed in this sort of study are not real anyway (Ioannidis, 2005). The inflation of the strength of associations is expected to be bigger in small studies, so it is noteworthy that the large meta-analysis by Larsson & Wolk, 2006 comments “In the present meta-analysis, the magnitude of the relationship of processed meat consumption with colorectal cancer risk was weaker than in the earlier meta-analyses”.
This is all consistent with the well known tendency of randomized clinical trials to show initially a good effect of treatment but subsequent trials tend to show smaller effects. The reasons, and the cures, for this worrying problem are discussed by Chalmers (Chalmers, 2006; Chalmers & Matthews, 2006; Garattini & Chalmers, 2009)
What do randomized studies tell us?
The only form of reliable evidence for causality comes from randomised controlled trials. The difficulties in allocating people to diets over long periods of time are obvious and that is no doubt one reason why there are far fewer RCTs than there are observational studies. But when they have been done the results often contradict those from cohort studies. The RCTs of hormone replacement therapy mentioned above contradicted the cohort studies and reversed the advice given to women about HRT.
Three more illustrations of how plausible suggestions about diet can be refuted by RCTs concern nutritional supplements and weight-loss diets
Many RCTs have shown that various forms of nutritional supplement do no good and may even do harm (see Cochrane reviews). At least we now know that anti-oxidants per se do you no good. The idea that anti-oxidants might be good for you was never more than a plausible hypothesis, and like so many plausible hypotheses it has turned out to be a myth. The word anti-oxidant is now no more than a marketing term, though it remains very profitable for unscrupulous salesmen.
The randomised Women’s Health Initiative Dietary Modification Trial (Prentice et al., 2007; Prentice, 2007) showed minimal effects of dietary fat on cancer, though the conclusion has been challenged on the basis of the possible inaccuracy of reported diet (Yngve et al., 2006).
Contrary to much dogma about weight loss (Sacks et al., 2009) found no differences in weight loss over two years between four very different diets. They assigned randomly 811 overweight adults to one of four diets. The percentages of energy derived from fat, protein, and carbohydrates in the four diets were 20, 15, and 65%; 20, 25, and 55%; 40, 15, and 45%; and 40, 25, and 35%. No difference could be detected between the different diets: all that mattered for weight loss was the total number of calories. It should be added, though, that there were some reasons to think that the participants may not have stuck to their diets very well (Katan, 2009).
The impression one gets from RCTs is that the details of diet are not anything like as important as has been inferred from non-randomised observational studies.
So does processed meat give you cancer?
After all this, we can return to the original question. Do sausages or bacon give you colorectal cancer? The answer, sadly, is that nobody really knows. I do know that, on the basis of the evidence, it seems to me to be an exaggeration to assert that “The evidence is convincing that processed meat is a cause of bowel cancer”.
In the UK there were around 5 cases of colorectal cancer per 10,000 population in 2005, so a 20% increase, even if it were real, and genuinely causative. would result in 6 rather than 5 cases per 10,000 people, annually. That makes the risk sound trivial for any individual. On the other hand there were 36,766 cases of colorectal cancer in the UK in 2005. A 20% increase would mean, if the association were causal, about 7000 extra cases as a result of eating processed meat, but no extra cases if the association were not causal.
For the purposes of public health policy about diet, the question of causality is crucial. One has sympathy for the difficult decisions that they have to make, because they are forced to decide on the basis of inadequate evidence.
If it were not already obvious, the examples discussed above make it very clear that the only sound guide to causality is a properly randomised trial. The only exceptions to that are when effects are really big. The relative risk of lung cancer for a heavy cigarette smoker is 20 times that of a non-smoker and there is a very clear relationship between dose (cigarettes per day) and response (lung cancer incidence), as shown above. That is a 2000% increase in risk, very different from the 20% found for processed meat (and many other dietary effects). Nobody could doubt seriously the causality in that case.
The decision about whether to eat bacon and sausages has to be a personal one. It depends on your attitude to the precautionary principle. The observations do not, in my view, constitute strong evidence for causality, but they are certainly compatible with causality. It could be true so if you want to be on the safe side then avoid bacon. Of course life would not be much fun if your actions were based on things that just could be true.
My own inclination would be to ignore any relative risk based on observational data if it was less than about 2. The National Cancer Institute (Nelson, 2002) advises that relative risks less than 2 should be “viewed with caution”, but fails to explain what “viewing with caution” means in practice, so the advice isn’t very useful.
In fact hardly any of the relative risks reported in the WCRF report (2007) reach this level. Almost all relative risks are less than 1.3 (or greater than 0.7 for alleged protective effects). Perhaps it is best to stop worrying and get on with your life. At some point it becomes counterproductive to try to micromanage `people’s diet on the basis of dubious data. There is a price to pay for being too precautionary. It runs the risk of making people ignore information that has got a sound basis. It runs the risk of excessive medicalisation of everyday life. And it brings science itself into disrepute when people laugh at the contradictory findings of observational epidemiology.
The question of how diet and other ‘lifestyle interventions’ affect health is fascinating to everyone. There is compelling reason to think that it matters. For example one study demonstrated that breast cancer incidence increased almost threefold in first-generation Japanese women who migrated to Hawaii, and up to fivefold in the second generation (Kolonel, 1980). Since then enormous effort has been put into finding out why. The first great success was cigarette smoking but that is almost the only major success. Very few similar magic bullets have come to light after decades of searching (asbestos and mesothelioma, or UV radiation and skin cancer count as successes).
The WCRF report (2007) has 537 pages and over 4400 references and we still don’t know.
Sometimes I think we should say “I don’t know” rather more often.
More material
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Listen to Ben Goldacre’s Radio 4 programmes. The Rise of the Lifetsyle Nutritionists. Part 1 and Part 2 (mp3 files), and at badscience.net.
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Risk The Science and Politics of Fear, Dan Gardner. Virgin
Books, 2008 -
Some bookmarks about diet and supplements
Follow up
Dan Gardner, the author of Risk, seems to like the last line at least, according to his blog.
Report of the update, 2010
The 2010 report has been updated in WCRF/AICR Systematic Literature Review Continuous Update Project Report [big pdf file]. This includes studies up to May/June 2010.
The result of addition of the new data was to reduce slightly the apparent risk from eating processed meat from 1.21 (95% CI = 1.04-1.42) in the original study to 1.18 (95% CI = 1.10-1.28) in the update. The change is too small to mean much, though it is in direction expected for false correlations. More importantly, the new data confirm that the dose-response curves are pathetic. The evidence for causality is weakened somewhat by addition of the new data.
Dose-response graph of processed meat and colorectal cancer
