Richard Asher: Straight and Crooked Thinking In Medicine

Dr Richard Asher made many excellent contributions to critical thinking as part of medical practice in the UK; one of the most entertaining of these was: Straight and Crooked Thinking In Medicine (pdf). Read it and savour it for the many useful and well-expressed observations. I’m going to highlight two that came up recently in different contexts (I’m separating them out with a rule but they are quotations and it seems easier to read than the standard blockquote).



Use of Vitamins
If I had to suggest one particular field of therapy which needs to come under the scrutiny of statistical clinical trial it is the use of vitamins. More than two million pounds’ worth of vitamins are prescribed each year under the National Health Service, and evidence that they do much good is very scanty. Are we not accepting arguments of this kind: (1) people deprived of vitamin B have sore tongues, (2) therefore everyone with a sore tongue needs extra vitamin B; (1) people deprived of vitamin C heal their wounds slowly, (2) therefore everyone with a wound needs vitamin C. These arguments alone are not rational-for instance, people deprived of salt for long enough may become mentally confused, but not everyone who becomes mentally confused needs salt.

The laity, too, have got the idea that as vitamins are essential to life any food that is full of vitamins is extra good for them. Subconsciously, I think they have adopted a sort of mathematical crooked argument that A is good, therefore 2A is twice as good and infinity x A is infinitely good. This is a dangerous argument. Cobalt, for instance, is (in minute quantities) essential to life, so is sulphur, yet a diet saturated with these substances might prove fatal…

But to return to vitamins the reason why they provide such a glorious field for the polytherapist and the commercial chemist is that they are more or less harmless (apart from very heavy doses of vitamin D). Therefore any doctor can prescribe them with the argument, “If you have vitamin deficiency,.they will do you good; if you haven’t vitamin deficiency, they can’t do you harm therefore logically we might as well prescribe them for everyone.” This argument is dangerous for these reasons: (1) by extending the argument we would find ourselves giving every member of the population an enormous number of vitamins and drugs; (2) if people are given vitamins they receive an impression that their diet is defective; (3) the cost to the country is enormous; and (4) people receiving a form of treatment (even if it is prophylactic) are more liable to believe they are unhealthy.

In our attitude to preventive medicine we have got to be careful that too much of the “can’t do harm might do good” argument does not lead to an excess of prevention. We must not be so busy preventing disease that we have no time to enjoy freedom from it…[pg. 461]

Causes
Another perversion of thought applicable to statistics is to believe that a statistical relationship between two things implies a causal relationship between them. It does not do so. It is very probable that statistics would show erythroblastosis foetalis to be twenty times less common among the offspring of opium smokers. This is no argument for encouraging opium smoking in the maternity wards. It depends on the fact that opium is largely a Chinese habit and that 99% of Chinese are rhesus-positive, and so cannot produce erythroblastosis foetalis. Similarly, if rheumatic fever is significantly more common in those who have sucked dummy teats in childhood, it may only mean that rheumatic fever is commoner among the poor, and so is dummysucking. If A varies with B, it does not show that A causes B. [pp. 461-2.] [Asher R. Straight and Crooked Thinking In Medicine (pdf). Br Med J. 1954 Aug 21;2(4885):460-2.



Asher might be a little wary of the news that a recent pilot initiative to reduce the number of frequent attenders at a GP’s surgery, 9 frequent attenders consented to a meeting with the manager of their local MIND at which:

[r]esolutions involved a range of ideas including volunteer work, subsidised reflexology, anxiety groups and subsidised counselling.

Those ideas are largely unexceptional but it might depend on whether reflexology had been presented as ‘a nice foot massage’ or as a therapeutic intervention that ‘might unblock energy flows’ or ‘correct imbalances’.

Several of Asher’s observations have had a profound influence and contributed to the groundswell of support for evidence-based medicine. However, it is with some tristesse that I must acknowledge that Asher would probably be very annoyed that these strictures and observations are as relevant today as when he made them more than 50 years ago. No piece that quotes Asher would be complete without his best-known observation: Talking Sense.



It is important to realise that ideas are much easier to believe if they are comforting, and that many clinical notions are accepted because they are comforting rather than because there is any evidence to support them. Just as we swallow food because we like it not because of its nutritional content, so do we swallow ideas because we like them and not because of their rational content.

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7 Comments

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7 responses to “Richard Asher: Straight and Crooked Thinking In Medicine

  1. “I must apologize for the rather vague way I have wandered from one subject to another.”
    Heh – I might start using that as a signature on my blog.

    Seriously – thanks for providing yet more quality reading material. Will put this in the queue (I’ve still got Influence and Testing Treatments to finish – not to mention Bad Science to start…)

  2. Talking Sense is one of those excellent and useful books that you can take up and put down when you have a spare minute. You might enjoy a flavour of its style in Medicine in Quotations.

    Humane Health has a nice account of Asher’s 7 Sins of Medicine: obscurity, cruelty, bad manners, over-specialization, love of the rare, common stupidity and sloth.

  3. Times has an account of Britain’s first ‘reflexology trail’.

    Officially the trail is called a Barfuss Park. “Barfuss” is German for “barefoot”, and the parks are popular in Germany and Austria. Sebastian Kneipp, a Bavarian monk, developed the concept in the 19th century. He is the founder of a natural health system called Kneippen (pronounced knipen), a kind of waterborne reflexology. Kneipp believed that wading barefoot on wet grass or in shallow water stimulated the internal organs, strengthened the immune system and helped the body to heal itself.

    Now, 1 km isn’t much but I suppose that this counts as an outing and exercise so perhaps the MIND intervention might have more going for it than I thought (depending on the accompanying explanation).

    tbh – the remainder of the article seems to undercut such a fantasy.

    Reflexologists, who say that rubbing the feet (believed to correspond to different parts of the body) can improve a host of medical conditions, are supportive of the idea…

    Vitality-boosting the trails may be, but could the stimulus of a foot “gymnasium” be a substitute for reflexology? Rooney believes it’s unlikely. “Only the sole of the foot is in contact with these trails,” she says. “A skilled reflexologist will work the whole foot and pay attention to specific organ reflexes. They will also vary the pressure to the reflex areas depending on the client’s tolerance and the desired clinical outcome.”

  4. amazing how things that were correct are often still correct fifty-plus years later…?! shame that in the meantime we’ve had a veritable explosion of alt med nonsense, and it seems mainstream medicine contributes to this by defiantly ignoring what Asher and others have been saying for decades.

    nice post…!

  5. We did put this in the miniblog but Steve Novella has a nice comment on the recent National Health Interview Survey 2007 that indicates that there really isn’t that much CAM usage.

    most hard-core CAM modalities are used by a very small percentage of the population. Most are less than five percent. Only massage and manipulation are greater than 10 percent. These numbers are also not significantly different from 10 or 20 years ago – belying the claim that CAM use is increasing.

    Also, if you look through the specific indications for which these modalities are being used, most are for back pain, with arthritis and other pains next most common. Very few are being used for medical indications.

    Possibly, it seems like there is a lot because it is cheap editorial in newspapers or fillers on TV. Plus, I think a lot of us regularly see (say) new TCM outlets opening in high streets and it feels as if we are in an explosion.

  6. It is difficult to say whether usage is increasing, but in my anecdotal opinion supporters of CAM are much more self-confident about proclaiming their beliefs than five or ten years. Could that be because they think the evidence has vindicated them?

    The town where I live with a population of 26,000 has two health food stores when two years ago it had none. Possibly there are more people consuming these things on the fringes. My GP surgery now has a CAM practitioner giving advice on Friday mornings. That’s certainly a new innovation for this year.

    It does seem to me that there is a drip, drip, drip “there must be something in it” effect slowly eroding people’s skepticism.

  7. Distressingly, in health food/organic shops near where I live it seems that pills and similar are steadily taking up more space, leaving progressively less space for food. Extrapolating in a very unscientific way from this anecdata, I do wonder if profit margins play a role here: there’s a limit to how much you can sell rye bread or apples for, but some of these pill bottles are a *lot* more expensive.

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