Comments on: The Power of the Placebo: a skeptical view

By: Jon d

Jon d — Thu, 22 Apr 2010 00:18:28 +0000

There’s a more recent placebo effect paper by Moerman that you can read for free. http://www.annals.org/content/136/6/471.full if Ben Goldacre had accurately summarised his earlier work I’d sorta expect moerman to say something about 4 placebo pills being better at healing ulcers than 2 but he seems not to. There’s a graph showing that across placebo controlled trials of ranatadine on ulcers, placebo treated ulcers tended to heal better in the trials where the real pills were more effective… But seems to me that could be showing a lot of things apart from placebo effects… Perhaps some trials just simply had more optimistic ulcer measurers than other trials?

By: Mike

Mike — Wed, 21 Apr 2010 10:43:19 +0000

To be fair to Moerman, I don’t know that his paper claims that four pills make ulcers heal faster than two pills.

However, Ben Goldacre promotes Moerman’s findings in his lectures and books, stating (paraphrasing here) “gastric ulcers heal faster when you take four sugar pills instead of two sugar pills, and this is a evidence of the amazing power of the mind over the body”. He is certainly implying causation.

As I suggest in the article, in light of the NEJM article (plus a Cochrane report which I only became aware of after penning this article) which concludes that placebos have no objective effects, I’m inclined to think that the four pill/two pill effect is actually an artifact of the research process, not a real effect in the patient.

By: Stu

Stu — Wed, 21 Apr 2010 10:25:26 +0000

I agree with the Doc – good post!

Richard Dawkins touched on placebo in the God Delusion. I think it was in the chapter/section about people finding comfort in religion (I’ve loaned my copy out so can’t check).

A reassuring chat with a professional physician can sometimes be enough to make people feel better just by lifting their mood – as the Doc points out.

This is how woo treatments work – everybody I speak (argue) with about crystal healers etc always, without exception, say “But he/she is a really nice person who understood exactly what was wrong and it worked for me.”

Doctors – real doctors – have been using placebo to, in my opinion, good effect for a long time.

It’s still a lie I suppose but a white lie is sometimes justified though isn’t it?

By: Jon d

Jon d — Wed, 21 Apr 2010 10:16:15 +0000

Something else occurred to me last night. You can write it up as if the doctors shove the gastroscope down the patients throat and objectively measure the ulcers without so much as a ‘by your leave’ to their experimental subjects but it occurs to me that probably they gave it a bit of the ‘how are we feeling today Mr Jones? first like you’d expect in any other sort of examination.
*Even if the 2 and 4 pill trials were identical in every other respect* we still know from trials designed to investigate the placebo effect that placebo pills from flashy boxes are more effective at reducing subjective rating of the subjects own symptoms than those from plain boxes etc.
If the doctor assessing the size of the ulcer spoke to the experimental subjects and the subjects perception of their symptoms had been influenced by the type of placebo they’d been given that’d be a possible feedback mechanism for the patients subjective ‘improvement’ to feed back into the supposedly objective medical assessment of ulcer size. Doctors generally want their patients to feel better and believe what their patients tell them. Perhaps an improvement in the patients body language would be enough. So doctors being only human after all, it seems to me there’s a possibility that doc’ll be looking for confirmation of improvement before he even starts putting the pipe in. The experiments could have been designed so the ulcer size ratings were carried out on cctv by a second specialist who never saw or heard from the subjects but blinding the people rating the ulcers size from the experimental subjects who likely have been influenced by the superficial attributes of the placebo they’d been given would be, afaict, an unnecessary complication in trials designed to compare a treatment expected to be effective vs placebo.
Though of course you’d have to look at the experimental designs (behind the pay wall) for the ulcer trials to know for sure I suppose.
Hope I’ve made myself clear, let me know if not.

By: Jon d

Jon d — Tue, 20 Apr 2010 22:52:06 +0000

On the subject of comparing apples and oranges you’re looking at a medical paper (Hróbjartsson & Gøtzsche) in a medical journal and an anthropological paper (Moerman) from an anthropological journal. It’s possible that it’s both valid for anthropologists to scratch their chin over Moerman’s findings and for medics to not admit them to their canon above the status of anacdote.

Moerman found that taking four placebo pills makes gastric ulcers heal faster than taking two

I can’t see the full text of Moerman btw, Does he really say 4 placebo’s *make* ulcers heal quicker than 2 or does he say something less emphatic about correlation?
(Correlation famously does not imply causation)

By: Doc Bill

Doc Bill — Tue, 20 Apr 2010 12:13:59 +0000

Fascinating topic and a great review which has made me think at lots of levels. Clearly, when the end point is subjective, then the magnitude of a placebo effect can be affected by a whole raft of determinants, both inside and outside the patient. What about objective measurements like time to healing? Well, we know that mood has an effect upon the autonomic nervous system. If you are waiting for an interview or examination then all sorts of symptoms are common, sweating, dry mouth, abdominal pain etc, which are mediated via the autonomic nervous sytem. We know that gastric acid secretion and gut motility are controlled by the sympathetic and parasympathetic nervous system, so that if someones mood and beliefs are affected by a belief in a treatment, then there is a clear mechanism by which physiological events can occur. Cut down acid secretion and some ulcers will heal.

Im wittering a bit, but I’m a committed evidence based medicine doc and skeptic, but lets remember that absence of evidence is not the same as evidence of absence of an effect. Sometimes we’re not asking the right questions, sometimes we’re not going about finding the answers in the right way and sometimes its all just too hard!