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New blog: Placebo effects are weak and reflect regression to the mean

Discussion in 'Other Health News and Research' started by Woolie, Dec 14, 2015.

  1. Woolie

    Woolie Senior Member

    Placebo effects are weak: regression to the mean is the main reason ineffective treatments appear to work
    by David Colquhoun

    This blog sets out some of the reasons that we should be suspicious of people telling us the placebo effect demonstrates "the power of the mind over the body". It argues that most of the placebo effect is artefactual. That is, there's no real underlying change to the illness being treated, it just looks as though there is.

    The blog focuses particularly on what they call the "get-better-anyway effect", which can make it look as though people have improved from a placebo treatment, when really the placebo had nothing to do with it. The "get-better-anyway effect is defined like this:

    The get-better-anyway effect doesn't mean the person's cured or even recovered. It just means that most illnesses have fluctuating symptoms and that people are most likely to seek treatment when their symptoms are at their worst. Chances are, they'll soon be heading back into a better period, if thy just wait long enough.

    In the comments section (also by David Colquhoun)

    Okay, so he only mentions big pharma and what he calls "quacks". But psychotherapy and other behaviorual therapies are also benefiting massively from this effect.
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  2. alex3619

    alex3619 Senior Member

    Logan, Queensland, Australia
    He does mention this applies elsewhere, such as the efficacy of traffic cameras. Regression to the mean is a general phenomenon where (typically) weak statistical data is used to conclude something that is only really vaguely implied and may be wrong. An artefact is a good way to put it.

    Its another bit of language we can use regarding the PACE trial outcomes.

    PS In case I did not make it clear, this occurs in large part because the baseline is made at a peak in the data, and over time it will tend to show more like the average outcome. I think in psychiatric medicine based on subjective outcomes we have an additional bias built in because patients are essentially conditioned to give the responses the doctor or researcher want.
    Last edited: Dec 14, 2015
  3. SOC

    SOC Senior Member

    Any idea how big pharma is supposed to benefit from belief in placebo effect? o_O I would have thought pharmaceutical companies would prefer to sell expensive "real" medicines for real illnesses. Surely they're not getting rich off placebo pills. Do pharmaceutical companies even market dummy pills? Do doctors really give dummy pills in this day and age when anyone can look up the medication they were prescribed on the internet to see what it's really for?
    Last edited: Dec 14, 2015
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  4. Woolie

    Woolie Senior Member

    You're right, @SOC. The placebo effect in general is most beneficial to "open label" research - where people know whether they're getting the dummy or the real thing. And of course, virtually all psychotherapy/behavioural interventions are "open label". They say tht's okay because:

    1. You can't properly "blind" a behavioural study (people have to be aware of the treatment)
    2. The placebo effect is "real" and therefore is a legitimate component of any behavioural intervention.​

    I don't have to tell you how weak the second argument is. Given the recent evidence suggesting the placebo effect is largely artefactual, this argument just doesn't fly. Plus, it puts behavioural studies on the same level as even the most questionable alternative therapies.

    The first argument is not good either, you can control for many of the factors that induce a placebo response in various easy ways, even in a behavioural study. For example, create a "dummy" treatment, like relaxation therapy, and promote it as a treatment in the same way as the one of interest. Controls for participants' expectations, their degree of investment in the treatment, as well as the "get-better-anyway" effect.
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  5. Sean

    Sean Senior Member

    Good find, Woolie.

    I have been arguing for years that the placebo effect, while genuine, is vastly over rated and of little real world use. It must be controlled for in trials, of course, but beyond that, a big fat meh. :meh:

    It is one of the main reasons I am not a fan of Ben Goldacre, he is besotted with the placebo effect.

    Sound familiar?
    Last edited: Dec 14, 2015
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  6. A.B.

    A.B. Senior Member

    I don't think it's safe to assume that the difference between a placebo and no treatment is the placebo effect (in the sense of a mind body effect).
  7. Skippa

    Skippa Anti-BS

    I think the psyche effect can be explained, at least partially, because it takes so damned long to get your first appointment that you are already "regressing towards the mean" when you begin.

    Big Pharma get their benefits because A) maybe their treatments aren't as universally effective as they would have us believe in every case, and, B) their "soft options" like OTC painkillers have been successfully been portrayed as magical cure-alls that we reach for whenever we so much as stub our toe.
  8. Hip

    Hip Senior Member

    I read an article around 15 years ago saying that the placebo effect was mainly due to many illnesses or symptoms having a natural tendency to get better over time. So if you go to your doctor with some vague pains, even if he gives you no treatment for it, in many cases the pains will just clear up on their own.
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  9. barbc56

    barbc56 Senior Member

    I haven't had a chance to read the above, probably after the holidays, but I think there are a lot of misconceptions about the placebo effect, even among scientists. It's a fascinating subject.

    Interesting thread. Thanks @Woolie.:thumbsup:

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