Update on the placebo effect

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In my recent exchange with Elaine regarding homeopathy, the subject of placebo effects predictably arose.

I say ‘predictably’ because it seems to be that once proponents of ‘alternative therapies’ are backed into a corner, and finally realise that their treatments are no better than placebo, the next line of defense (or is it attack?) is: “well, the placebo achieved by our modality is very valuable and shouldn’t be under-estimated”. Elaine made that very claim.

It is therefore timely that this review by Dave Gorski, (nicely summarised by Steve Novella here), was published.

To summarise even further, here are the two critical graphs which  tell the story.

In this first graph (Figure 4), we have a subjective assessment of 4 different interventions by patients suffering asthma . Notice that the placebo inhaler and sham acupunctureare just as highly rated as the ‘real’ treatment. Wow, nice work Mr. Placebo.

Now look at Figure 3. In this case, instead of asking the subjects how they assess the improvement, we measure the lung function of each – a much more objective assessment of the treatment.

Hey presto, all of as sudden, the ‘real’ intervention is dramatically better.

The clear outcome is that treatment with placebo is barely better than no treatment at all. And, as a bonus, this also shows that the placebo inhaler is better than the  fake acupuncture – so the charade of magical modalities is unnecessary.

As another bonus, this study also addresses another claim made by Elaine in the dog study she cited, and also all the hoo-ha regarding Elmore Oil (too many articles to which to link – do a search on Elmore, here at rationalbrain). Even though she claims that dogs are not subject to placebo effects (an assumption which I questioned), it clearly shows the folly of relying on subjective assessments – and is the reason I suggested some sort of objective measure of whether there was any improvement in the condition.

Clearly, subjective assessments are notoriously unreliable in predicting real physiological effects, and simply ‘feeling better’ doesn’t cut it with significant illnesses.



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2 thoughts on “Update on the placebo effect

    Blamer .. said:
    July 21, 2011 at 5:22 pm

    An update for you from the Theraputic Goods Administration:

    http://www.tga.gov.au/pdf/consult/review-tga-transparency-1101-final-report.pdf

    “Concerns were also expressed over the lack of community understanding about homeopathic products, and their frequent availability in pharmacies. The view was put that consumers should be made aware of the lack of modern scientific evidence for these products, and that because of this, there may be serious questions about some advertising practices used.”

    “At both the consultative sessions and in submissions, it was asserted that many therapeutic claims, or claims regarding efficacy and safety made for complementary medicines, cannot be supported from the limited scientific evidence available, while information about possible adverse effects, especially their interaction with conventional medicines, is often lacking. However, complementary medicines are not permitted to state any interactions with conventional medicines in any material that could be considered advertising.

    It was accepted that the majority of complementary medicines are low-risk products, but low-risk does not mean no-risk. Submissions claimed that many complementary medicines are heavily promoted as ‘natural’ or ‘natural alternatives’, with the implication that they are harmless. It was said that this can result in consumers not advising their medical practitioner or pharmacist about their use, and that health practitioners often do not ask about them.”

      rationalbrain said:
      July 21, 2011 at 6:02 pm

      Thanks for this Blamer.
      I’ll need to have a good read of the report.
      I do have a quibble about the ‘low risk’ part. They are low risk for non-critical applications. But when they become a substitute for science based medicine, then the real risk kicks in.
      r.

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