Knowing who and what to believe in medicine and health

So Dr Andrew Wakefield and his two professor colleagues now seem to have been totally discredited, not just on the basis of their research’s conclusions, but also in terms of their ethical approach to their study’s child patients. In a final symbolic act the Lancet has today formally withdrawn its publication of the research. That may seem to draw a line under the whole affair, but a glance at the JABS website will disabuse you of any such conclusion.

It’s not my intention here to venture into any debate about the substantive scientific issues surrounding MMR vaccines and autism and bowel disease, but rather to reflect on what this and the many other instances of intra-medical warfare mean for the average punter in the street. How are we lay people to pick the bones out of these long-running and frequently bitter disputes between different camps? You’d think we’d at least have had plenty of practice. Off the top of my head I could mention: the debate about serum cholesterol, heart disease and statins; the efficacy of the prostate specific antigen test; the dangers or otherwise of dental amalgam; the disputes about water fluoridation; the controversy over aspartame. I could go on, but probably don’t need to. Added to these “running sores” of disagreement and confusion are the flashes of controversy sparked by articles in the press, the kind of stories that scream out that the risk of this, that, or the other has just been shown to have doubled or trebled. And which usually turn out to mean that the infinitesimally unlikely has graduated into the extraordinarily improbable.

This last thought makes me wonder if perhaps the best we can do is to develop a kind of defensive toolkit that might protect us from at least the grosser kinds of gullibility. Many ordinary citizens are woefully incapable of understanding probability or percentages, but can easily grasp concepts like doubling. Discovering that I’m now twice as likely to get run over as I was last night would almost certainly prompt me to take more care this evening; but if my chances were last night 1 in 1,000,000 perhaps I shouldn’t be all that concerned that they’re now 1 in 500,000. So I’d suggest the following few rules of engagement.

  • Make it your business to be confident in interpreting probabilities and percentages, and apply that understanding to all statistics you encounter.
  • Understand the difference between what can be said about populations and what can be said about a given individual such as you. Just because doing something can be shown to benefit an overall population doesn’t mean it will benefit you, and vice versa for something that might be harmful.
  • On the other hand, one swallow doesn’t make a summer. Knowing one person who smokes 80 a day and is 90 years old without even so much as bronchitis does not of itself invalidate 40 years of research.
  • Be aware of conflicts of interest: a drugs company is unlikely to take the view that you’ll be better off without its products.
  • Be careful when tempted to act either on fear or out of hope; eat blueberries if you like them, but not because you’re scared of cancer and someone’s said that they’re a wonder food with miraculous anti-cancer properties.
  • Remember that your body is a complex system in which there are an almost infinite number of interactions, and that single-purpose magic bullets with only one effect do not exist: everything has side effects.
  • Remember also that medical orthodoxy changes over time, and not infrequently contradicts itself. It is not always the case that the medical theory in the ascendancy is the one that’s correct. An old friend of mine was told by her doctor in the 50’s to start smoking for the good of her health!

None of this will tell you what to believe, or what to do, in the face of medical dispute. But taken together they might help you to resist being pushed from pillar to post by every pronouncement, be it from the medical establishment or from the medical mavericks.

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5 thoughts on “Knowing who and what to believe in medicine and health

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  2. An excellent set of “rules of engagement”. I trust that you don’t have to use them very often !

    When trying to understand a controversy, I would suggest the following rules of classification:

    The evidence is limited or uncertain (e.g. benefits of blueberries) — there is no good way of resolving differences of opinion.

    The evidence changes with new research (e.g. cholesterol and diet) — people who don’t follow the research won’t understand why recommendations change.

    The evidence is clear, but values differ (e.g drugs for Alzheimer’s) — discussion should aim to clarify reasons for differences in values.

    The evidence is clear, but the risks are misunderstood (e.g. screening for breast and prostate cancers) — communicating and understanding risk is key.

    The evidence is clear, but there are groups whose position is based on belief and aruments are based on emotion (e.g. homeopathy) — understanding different approaches requires understaning the placebo effect and how people are motivated by hope and fear.

    • A useful “controversy classification” scheme. I suspect that the issue that might cloud your schema is where there is controversy about whether the evidence is clear or not! And indeed disputes about what truly constitutes evidence. Nevertheless, I like your approach.

  3. my God, i thought you were going to chip in with some decisive insght at genuine end there, not leave it with ‘we leave it to you to decide’.

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