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How the placebo effect proves nothing and means nothing

Last updated on June 13th, 2012 at 05:09 pm

Recently, there has been a large uptick in interest about the so-called placebo effect, mostly from the complementary and alternative junk medicine (CAM) crowd.  Evidently, they feel that being equivalent to doing nothing is good enough to be real.  A recent article in the Wall Street Journal, Why Placebos Work Wonders, is indicative of this recent pro-placebo point-of-view.  I’ve got other bones to pick with WSJ on global warming, but I’ll save that for another day.

What exactly is the placebo effect?  The definition is often misused, implying some beneficial effect from a sugar pill or sham treatment.  But in medicine, a placebo is actually a failure.  If a new pharmaceutical, procedure or medical device shows no difference in efficacy compared to a placebo, then it is rejected.  But the CAM-pushing herd thinks that proves its a success when one of its potions and lotions is equivalent to a placebo.  What?  A failure of a modality in evidence-based medicine is somehow converted into a successful product in the CAM world?

[pullquote]there just is no evidence that the placebo effect has any effect in real pathologies[/pullquote]

What precisely is a placebo effect?

  • It can be just a random statistical variability, and if the study is repeated 100 times, it may disappear altogether.
  • It’s almost always a subjective effect, meaning that it’s not a condition where the researcher can actually measure the effect in a laboratory test.  If we find a drug that actually eliminates HIV from the body, we can measure that.  But most studies that measure a placebo effect in a CAM treatment, it’s some measurement that’s hard to quantify.  Less pain is a usual one.
  • The subjectiveness then leads to some induced bias into the study, including the observer-expectancy effect ,where the researcher’s bias influences the participants or even that the participant expects to feel better; experimental bias where the actual design of the experiment leads to a positive result; or the Hawthorne effect, where the participant modifies their behavior just because they are being observed.
  • Maybe there is some “mind over body” effect, but there are no known mechanisms for this kind of effect.  And to dispel the old logical fallacy of “the absence of evidence is not evidence of absence,” we have looked for a mind over body effect, but have not actually found one. That is, in fact, evidence of absence.  But as a real scientist, it is important to note that many of us will jump on board if a mechanism is found, but the only ones I’ve read, energy fields, or some mysterious compound in the blood, stand in firm opposition to the basic laws of physics and chemistry.  In other words, there better be some good evidence for such a mechanism, and there is none.

My issue remains that there just is no evidence that the placebo effect has any effect in real pathologies.  It cannot shrink tumors.  Oh sure, there might be some tumors that do shrink miraculously, but instead of assuming some magical response, I’m going to assume it’s not a miracle, but we just haven’t figured it out yet.  Yes, a good skeptic’s default position shouldn’t be “it’s a mystery we’ll never understand;” actually, it should be “it’s a mystery, let’s use science to understand it, because if we do, maybe we can cure everyone who has this disease.”  This isn’t an opinion, but the Cochrane Reviews (a group that does meta analyses of medical and scientific studies) made these comments in a review of placebo effects:

❝Placebo interventions are often claimed to substantially improve patient-reported and observer-reported outcomes in many clinical conditions, but most reports on effects of placebos are based on studies that have not randomised patients to placebo or no treatment. Two previous versions of this review from 2001 and 2004 found that placebo interventions in general did not have clinically important effects, but that there were possible beneficial effects on patient-reported outcomes, especially pain. Since then several relevant trials have been published.We did not find that placebo interventions have important clinical effects in general. However, in certain settings placebo interventions can influence patient-reported outcomes, especially pain and nausea, though it is difficult to distinguish patient-reported effects of placebo from biased reporting. The effect on pain varied, even among trials with low risk of bias, from negligible to clinically important. Variations in the effect of placebo were partly explained by variations in how trials were conducted and how patients were informed.❞

Simply put, there really are no placebo effects, except in patient reported outcomes, which are subject to all the biases I mentioned above.

I was about to end the article right there, except while I was reading articles on the placebo effect I ran across How the Placebo Effect Proves That God Exists by Richard Schiffman the Huffington Post.  Before I can start, I find HuffPo’s anti-science bias far more egregious than those I find in right-wing media like the Wall Street Journal.  In fact, it was chosen as one of the 10 most anti-science websites, along with the 9/11 denialists, the Australian Vaccine Network (to be discussed in a future posting), and Answers in Genesis amongst others.

Nevertheless, Schiffman uses the argument because we don’t know what causes the placebo effect, it is a proof of some deity.  Wait, just because we don’t know what causes it, we then leap to some random conclusion, an argument from ignorance fallacy.  In other words, arguments from ignorance infer that a proposition is true from the fact that it is not known to be false.

At any rate, Shiffman’s article is mostly a confusing discussion of trying to prove god exists, then makes this statement:

❝Which brings us back to the placebo effect. It is mysterious, right? We don’t know how it happens. A person was sick and they take a sugar pill and next thing you know — voila — they are healthy. To call this “the placebo effect” is to dress up our ignorance in words. What has actually happened is nothing short of a miracle. Science has got no explanation for it– something immaterial (a thought?) has impacted something material (our body) in a way which utterly defies logic.

And that is what prayer is all about. Prayer is based upon the conviction that the immaterial is more powerful than matter itself. Whether we call this immaterial force “God,” “the ground of our being,” “Spirit,” or “higher consciousness” doesn’t matter. The point is– there is an uncanny power (which all of us without exception have got access to) which performs miracles. The sick can be cured, the broken can feel whole again.❞

Wait, but we don’t have any evidence that the placebo effect exists.  And science can explain almost everything about the placebo effect.  This is not a proof of anything, let along the existence of deities of any sort.

Remember, a placebo effect is a failure, it is not a success.  To use a failure to support an affirmative belief is just illogical.

Michael Simpson

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