Evidence-free zone

The big thing in modern medicine is evidence.

The story goes, so long as there is no evidence, what you are doing could be wrong.

This is philosophy based upon the null hypothesis – a scientific method where you start with a position that pepper, drug P, or whatever has no effect on lifespan, symptoms or length of stay and you either prove or disprove the theory.

The less likely an event is to happen by chance the more likely there is an effect. In science, we take less than one time in 20 as being ‘statistically significant’ – sometimes we refer to this as a p value of <0.05.

I won’t go into this in any more detail as it is likely some of what I have already said is wrong. If in doubt, perhaps check Google.

The thing with medicine is that despite our beliefs that so much of what we do is evidence-based, so much consistent with the rigours of the scientific method, it is only the very tip of the iceberg (or the tip of a Polar Bear standing on a very long ladder on an iceberg).

Most of what we do is based upon experience, best practice, feeling, hunch.

I have covered this before – the impression patients have that the word of a doctor is anything approaching absolute:

Doc (2)

‘You have a nasty case of pneumonia.’

‘The other doctor told me it was a chest infection.’

‘No, definitely pneumonia.’


Doc (3)

‘You have a urine infection.’

‘Doctor 2 told me pneumonia.’

‘No, your chest is clear, it is bugs in the urine.’


Doc (4)

‘Why am I breathless?’

‘It is a blood clot’

‘Doctor 1 said chest infection, doc 2 pneumonia, doc 3 urine and you are telling me a clot?’

‘Yes, a clot.’


This is not a demonstration of incompetence, it is just the uncertainty, the greyness that is central to many aspects of clinical medicine.

And this is why I am always surprised when I hear colleagues in their certainty, quoting evidence – particularly when they don’t stop there, as in, ‘There is evidence that drug A is better than drug B,’ but, go into detail, ‘Drug A is 2.12 times better at treating your infection than drug B’ – the more you up the ante, the more confident folk become, ‘In a 2012 study published by O’Hare et al in the Lancet, drug A in a double-blind, placebo-controlled trial was shown to be 2.12 times better than drug B at treating pneumonia. Here, have drug A.’

That is OK so long as you have pneumonia and it isn’t a blood-clot that is causing your symptoms, then drugs A and B are equivalent and the researchers needn’t have bothered.

Again, I am not trying to diminish the importance of this work – it is how we learn and progress; what is key however is that we don’t lose sight of uncertainty, of what we don’t know.

Strip away law and order, the internet and microwave ovens and you will soon discover that essentially, we are still the same vulnerable humanoids that left East Africa two million years ago.

Sure, you want a degree of confidence from your doctor – you don’t want them expressing uncertainty when you are feeling vulnerable, but, and here are the two main points – don’t overly focus on the evidence, for this is just part of an unfolding story that one day we will look back upon and laugh, and, no matter the evidence, it is first the context, then far more important the preferences, the interpersonal that makes all the difference.

Why is my prescription for paracetamol so much more effective than a blister-pack from Tesco? It is the ceremony, the performance, the medicalised placebo.

So, yes, I’m a doctor, part scientist, part shaman, and a little bit trickster.

Trust me.


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Published by rodkersh1948

Trying to understand the world, one emotion at a time.

2 thoughts on “Evidence-free zone

  1. Great blog, so true!
    I’ve always called being a good doctor being able to talk bullshit but Shaman and trickster are much better words I will now use.

    Liked by 1 person

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