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5:56 AM
Patients were randomized to either open-label placebo pills presented as “placebo pills made of an inert substance, like sugar pills, that have been shown in clinical studies to produce significant improvement in IBS symptoms through mind-body self-healing processes” or no-treatment controls with the same quality of interaction with providers.
And the open label placebo pills did better than no treatment.
 
 
4 hours later…
10:26 AM
@HappySpoon I've never read the study. The first I heard of it was criticism when it came out.
 
 
5 hours later…
3:06 PM
We're at the point in the research where individual studies on the issue should not be assessed in isolation. But even looking at this one study it has methodological weaknesses.
The experiment was not blinded
Also in both groups, individuals were allowed to continue their previous IBS medication.
People that know they're being monitored for one intervention are likely to increase compliance with unrelated beneficial interventions (like their preexisting medication)
The patients knew what was being tested and were told that the placebo was expected to be effective
I.e. they were told that it had a mechanism of action and an effect.
Thus all of the subjective endpoints would be subject to the expectation effect... Individuals answering towards what they think the experimenter wants to find.
Last, they did 4 comparisons without correcting the significance tests for multiple comparisons.
Normally, when you do multiple comparisons you apply something like the bonferroni correction to reduce the family-wise false positive rate
One more thing. They did not check how many of the subjects in each group were using preexisting medication and they didn't rule out increased compliance with preexisting medication as the explanation for this effect.
(If there was an effect to explain at all)
Some of these weaknesses were acknowledged by the authors in the discussion section. They said this should be seen as a "proof-of-principle" pilot study. However they fail to acknowledge that there may not even be an effect. And none of their cautiousness ends up in the abstract.
They say more research is needed and on other conditions etc.
In my opinion, while that may be true, it jumps the gun. What is needed is a better controlled replication of this experiment first.
Hmmm.. They find it "counterintuitive" that their experiment yielded larger effect size than the placebo groups in double-blinded IBS studies.
That seems to indicate they have an underestimate of the problem that the report bias (desire to please the experimenter) can introduce.
Interesting that at the end they asked the participants what they thought was in the pill to check whether they thought they were "really" receiving a placebo. They didn't ask them whether they thought the pill was invoking an clinically proven mind-body connection, the mechanism they were told about at the outset.
 

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