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Evidence-based medicine

"What if we tried to practise medicine according to the best evidence, only to find that half of it was mssing?" asks Minerva, in today's BMJ. In fact, as she goes on to say, that is exactly our position. She lllustrates this by citing a Cochrane review of a treatment for venous leg ulcers using flavonoid supplements. A previous review had found some support for this although the trials were mostly not good quality. Now a better trial has come to light; it was conducted by the manufacturers and did not find evidence of better healing. it was left unpublished.

Advocates of unorthodox treatments are often criticised for not providing convincing evidence of efficacy, and this criticism is often justified. But what is usually glossed over is the fact that orthodox treatments are usually in not much better shape.

The previous week Minerva reported a Canadian randomised trial of naturopathy that was published in the Canadian Medical Journal. The "more orthodox facets" of this treatment were compared with usual care to reduce cardiovascular risk factors and body mass index. Naturopathy proved more effective, and the methodolocical failings were no greater than those that are found in many similar trials of orthodox treatments.

It's not that we don't need evience of effectiveness in medicine - we do - but it's a lot harder to come by than we often think.

Medical error in 'Endeavour'

In ITV-1's 'Endeavour', the youthful Morse, still a detective constable at this early stage of his career, found a girl who had died with digoxin in her stomach. "Is that dangerous?" he asked a GP who was involved in the case peripherally (the partner of another doctor who was murdered).

"It certainly is. The clue is in the name of the plant it comes from, deadly nightshade," the GP replied.

But deadly nightshade doesn't give us digitalis or digoxin, it gives us belladonna. Digitalis, from which digoxin is derived, comes from the leaf of the foxglove. I thought that perhaps this wasn't really a medical howler and we were being given an artfully planted clue; the GP was going to turn out to be an imposter. But no, it wasn't the doctor who was ignorant, it was his creator.

Misleading remark on BBC about antibiotic resistance

This morning, James Naughtie was commenting on the Chief Medical Officer's warning about increasing antibiotic resistance. He said "our bodies are becoming resistant ." It's not our bodies, of course, it's the bacteria, providing a classic example of Darwinian natural selection in action.

More diet 'wisdom' questioned.

My father, who died peacefully in his late eighties, ignored recommendations to avoid eating saturated fat, saying that he had eaten butter all his life and it had never done him any harm. It seems he may have been right.

This week's BMJ has a research paper and accompanying editorial questioning the American Heart Association's advice on diet to prevent heart disease. The Association recently repeated its advice to maintain and even increase your intake of linoleic acid, which is found in high concentration in vegetable oils such as corn, sunflower, safflower, and soybean oils. We are supposed to use these oils in preference to saturated fat.

There is little objective evidence to show that exchanging linoleic acid for saturated fat does any good. Most trials of this hypothesis have involved other dietary changes and/or other interventions. And the new research suggests that increasing linoleic acid may actually be bad for you.

The researchers, Ramsden and colleages, looked at the original data from the Sydney Diet Heart Study, a randomised controlled trial conducted between 1966 and 1977 and involving 458 men aged 30 to 59 who had had a recent coronary event. Total serum cholesterol was lowered in those taking an increased amount of linoleic acid but deaths from heart disease were not reported in the original paper.

The new research is based on a re-examination of the original data (a technically difficult task). They found that mortality due to heart disease was higher in the group taking increased linoleic acid. Notice that this happend even though the serum cholesterol level in these men was reduced.

These findings contradict the view that replacing saturated fat with linoleic acid is a good idea. They do agree with what Gary Taubes contends in The Diet Delusion, in which he claims that saturated fat is not harmful.

What strikes me particularly about this is that the original researchers assumed unquestioningly that reducing serum cholesterol would automatically lead to a reduction in deaths from coronary heart disease. It didn't, and in fact their intervention actually increased the death rate from this cause.

Telomeres - the latest "scientific"(?) way to tell your fortune

Today's Independent has a piece about having your telomeres measured. These sequences at the ends of chromosomes are alleged to give an indication of how far your biological age differs from your chonological age. The longer they are, the longer you are likely to live. The test is now available commercially; it's still expensive but is forecast to become increasingly cheaper in coming years, to the point where everyone will be able to afford it.

The one prediction I'm prepared to make is that it will be a money-spinner for the Spanish company that markets it. Professor Carol Greider, who won a Nobel Prize for her work on telomeres in 2009, is sceptical about the value of the test but that won't prevent many thousand or millions of people from taking it. Another egregious example of useless screening. Plenty more about this in my blog - search for "screening" with the search button on the right for links.

Scepticism, homeopathy, and the Swiss Government report

For some reason the fact that the Swiss Government had produced a favourable report on homeopathy had escaped my notice until today, but when I learnt of it I looked it up on the net. This brought me to the Quackometer site, which has a discussion of the report called The Swizz report on homeopathy.

Well, of course, you'd expect the Quackometer to be critical of a report that supports homeopathy, but fortunately their piece contains some quotations from the Swiss article which help us to make up our own minds..

The current thinking and research of mainstream medicine are influenced mainly by Newton’s mechanistic and strictly causal-analytical physics (classical reductionist biomedical model), which ignores the more complex phenomena of nature, the organism’s systemic correlations, its life processes and overall regulation, and life as a whole, as well as qualitative experiences and the phenomena of spiritual science.

This passage is a complete give-away, particularly the reference to spiritual science. This will no doubt puzzle many readers, but anyone who knows anything about Anthroposophy, the so-called "Spiritual Science" founded by the philosopher and mystic Rudolf Steiner in the first half of the twentieth century, will recognise the term at once. It seems certain that Anthroposophical influences helped to shape the authors' conclusions.

So Newton is outmoded and a waste of time but science is not a total washout, it seems. Further on, predictably, we are told that homeopathy is supported by quantum physics.

Modern physics with its theory of relativity and quantum physics has long overtaken Newtonian mechanics and is paving the way for an understanding of the homeopathic mechanism of action.

Since few of us who are not trained physicists have any deep understanding of quantum mechanics or relativity we mostly have to rely on non-mathematical descriptions of these things written for readers like us. Some of these are very good, but physicists assure us that verbal accounts cannot give an in-depth understanding of the matter. Quantum mechanics is often invoked to explain the action of highly dilute homeopathic medicines. Often, I think, this amounts to little more than asserting that quantum mechanics and homeopathy are both mysterious, so they ought work in the same way. Moreover, if science can tolerate the paradoxes of quantum mechanics, why baulk at homeopathy?

Just to round off, I should point out that we even get the long-discredited idea of the vital force.

The vital force, just as vitality in general, cannot be measured and quantified by science, but it exists as a phenomenon.

I admit I haven't read the whole of this (long) report and perhaps some parts of it are better. But at least it seems clear that its authors are hostile to the values of the Enlightenment, which is enough to move it a long way down my reading list.

Values of health checks, breast screening, flu vaccine questioned

The BMJ of 24 November 2012 has a Cochrane systematic review and metanalysis that questions the value of routine health checks. Not only do they fail to prevent death or illness, they may also cause harm through unnecessary investigations or treatment.

We did find that health checks led to more diagnoses and more medical treatment for hypertension, as expected, but, as these did not improve mortality or morbidity, they may be considered harms rather than benefits.

The same issue of the BMJ also has a piece about screening for breast cancer. It reports an article in The New England Journal of Medicine which finds that screening has led to the overdiagnosis of breast cancer in 1.5 million women in the USA in the last 39 years. Mammography only marginally reduced the rate at which women presented with advanced cancer. Although death from breast cancer has reduced considerably over this period, the reduction is mainly due to better treatment, not screening.

Here are a couple of quotes from the article in the NEJM.

Our study raises serious questions about the value of screening mammography. It clarifies that the benefit of mortality reduction is probably smaller. and the harm of overdiagnosis probably larger, than has been previously recognized.

Although no one can say with any certainty which women have cancers that are overdiagnosed, there is certainty about what happens to them: they undergo surgery, radiation therapy, hormonal therapy for 5 years or more, chemotherapy, or (usually) a combination of these treatments for abnormalities that otherwise would not have caused illness.

Finally, there is an article citing a report from the University of Minnesota which says that the effectiveness of 'flu vaccination has been greatly overestimated, at least for the over-65s for whom it is mainly recommended. There is no harm in having the vaccine, but it should certainly not be made compulsory fo health workers, as is increasingly happening.

NICE and headaches due to analgesic over-use

I was interested to hear today that NICE has now told doctors and patients that taking too many analgesics can cause headaches. This has been known for over 20 years; I was first made aware of it when I attended a symoposium on headache at the National Hospital for Nervous Diseases some time in the 1990s. Since then I have seen a number of patients whose life was transformed by telling them to stop taking the tablets, 'Cold turkey' seems to work best; I warned them they would have six weeks of hell, after which their headaches would largely disappear. I have always mentioned it while teaching acupuncture to health professionals.

It seems odd that it has taken so long for NICE to come out with this 'discovery'.

Poor-quality paper on low-carbohydrate high-protein diets in BMJ

The current issue of the BMJ (7 July 2012) has a research paper by Pagona Lagiou and others on the incidence of cardiovascular disease in over 43,000 Swedish women who were following low-carbohydrate high-protein diets. They found a dose-related association, with those following the diet most strictly being at biggest risk.

An accompanying editorial points out that most studies of diets of this kind have been short-term. They have found improvements in risk factors for heart disease and this has encouraged the idea that these diets are safe. But their long-term safety is questionable, the editorial suggests, and low-carb high-protein diets should therefore not be advised to patients at present.

This contradicts what Gary Taubes famously advocates in The Diet Delusion. But if you have been persuaded by him to follow a low-carb diet and are finding it suits you (as I am), don't immediately rush off and start stuffing yourself with carbohydrates. Instead, go to the BMJ site ( and read the rapid responses to the article. So far there are 12 all unfavourable or downright dismissive.

The correspondents give numerous reasons for these unfavourable opinions. I'll cite just one: the average duration of the diet period was 15 years yet the nature of the women's diet was established simply by a single questionnaire given at the outset. Yes, that's right: no folllow-up assessment!. Can you honestly say you've eaten the same diet for the last 15 years? Could we believe you if you did? I could scarcely believe that this was what the paper is based on when I first read it, but it is.

Several commentators say that the article should not have been published, let alone endorsed by an editorial. One, a (Swedish) paediatrician, describes it simply as a total disaster.

If you are following a low-carb diet there is no need to panic just yet.