Friday, December 24, 2010


Someone’s high on placebos

On Wednesday, this paper, published in PLoS ONE, hit the popular news in the medicine/science category, with articles such as this one from MedPage Today and this, from Reuters. The headlines are consistent, implying that the study has shown that the placebo effect works even when patients know that they’re getting placebos.

From the MedPage article:

While this may seem counterintuitive, the results suggest that physicians don’t have to resort to deception to harness the power of the placebo effect, Kaptchuk explained in an interview.

Conventional wisdom says that in order for a placebo to work you have to convince the patient that they are taking a real drug, he told MedPage Today.

However, the brain appears to respond to placebo in a way that conditions like IBS are susceptible to, Kaptchuk noted.

Counterintuitive, indeed, and enough so that it merits some serious scrutiny. My first thought was that the headlines are misrepresenting the study and the claims of the researchers, a common problem in the reporting of research in the popular press. But it seems that they are, indeed, reporting exactly what the researchers are saying, here.

I’ll note that the paper appears in a Public Library of Science (PLoS) journal, rather than in some other, more respected medical journal (such as NEJM or BMJ). I’ll also note that the lead researcher, Ted Kaptchuk, is associated with Harvard’s Division for Research and Education in Complementary and Integrative Medical Therapies, a connection the press just puts forth as Harvard, downplaying the fact that he does complementary medicine.

Those aren’t reasons to ignore his research or his results, of course. But they are points that should make us ask questions. On the other hand, we should ask questions with any study; that’s what science is about.

Now, the study is on IBS, which is a very subjective, catch-all condition of unknown etiology. They mention in the article that they expect this effect to work also with conditions such as fibromyalgia and chronic pain — also subjective conditions of unknown etiology — and depression and anxiety, more highly subjective stuff. And the study itself is entirely subjective, using self reporting exclusively, and not measuring anything.

That could be OK. If we’re looking for cures, we need to measure; if we’re looking for symptom relief, well, if you think you feel better, then you feel better. Where I have to scratch my head, though, is in wondering what their hypothesis was.

When you go into a study, you go in with a hypothesis, which your study might support or disprove. Even if it seems like you’re just wildly trying any drug that might work, you have a hypothesis: This drug might work. What’s the hypothesis, here? Placebos might work even if the patients know they’re placebos, is a valid hypothesis, I suppose, but to whom would it occur to even try that?

The answer shows up in the study: it would occur to people who think they can show mind-body self-healing processes. OK... again, a valid thing to consider. But that’s where we get into some problems.

We start with some very typical problems with medical studies... again, from MedPage:

Limitations of the trial included a relatively small sample size, too short duration to examine long-term effects, and the possibility of self-selection bias in that the trial may have selectively attracted IBS patients interested in mind-body interventions.

Many, many studies are too small, too brief, and suffer from various sorts of selection bias, and this one is no different. But to get the real kicker, we have to go into the paper itself and see how the placebos were presented to the patients:

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.

Read that again. The patients were not told just that they were getting placebos. They were not told that what they were getting is an inert substance with no medical effect. They were told that what they were getting has been shown in clinical studies to produce significant improvement in IBS symptoms.

In other words, these pills are having exactly the same placebo effect as is well documented in pretty much every other medical study that involves placebos. And, to put the point forth directly, far from making this deception-free, they are deceiving the patients in the same way patients are deceived in every other administration of placebos.

Let’s line it all up:

  1. You recruit people who have a condition that makes them feel horrible, that no one can tell them the cause of, and that no one has effective treatment for.
  2. You give them a pill and you tell them that this has been shown to provide significant improvement for their condition.
  3. They report that the pills did, indeed make them feel better.
  4. You claim that you did not deceive them, because you told them they were getting placebos.

Bullshit. Whether or not you put the label placebo on it, you told them they were getting effective treatment. That biased the outcome, and the result should be no surprise to anyone. And it says... nothing. This study is worthless garbage.


Thomas J. Brown said...

Who funds this stuff? Didn't anyone bother to ask for a proposal before hand? "What's your hypothesis? How will you select candidates? How will testing be administered? Over what duration of time will the testing occur? How will results be measured?" It seems like there's a failure on both ends with this one.

polemarkh said...

Who funds this stuff? The National Centre for Complementary and Alternative Medicine (NCCAM), of course. Who would you expect to fund it?