If Placebos Work, Why Placebo-Controlled Trials?
Placebos have been a hot-button issue in human-subjects research ethics for years. Many regard placebo-controlled trials as the “gold standard” for clinical research. Others see the use of placebos in clinical research as typically-unjustified (at least in cases where a decent treatment exists). (To get a sense of this debate, check out this article by Charles Weijer: “Placebo trials and tribulations”.)
So it has been interesting to see placebos popping up as a topic of discussion lately. Placebos are supposed not to work. That’s the whole point of a placebo-controlled trial — to compare an experimental drug against something “known” not to work, in order to make sure that any positive effects observed aren’t merely the result of the “placebo effect,” i.e., roughly the psychological result of patients feeling cared-for.
But if placebos are (by whatever mechanism) more effective than previously thought, that kind of throws a monkey wrench into the equation.
As a starting point, see this Wired article: Placebos Are Getting More Effective. Drugmakers Are Desperate to Know Why.
For a more scholarly look at a complication, see this PLoS One article by Kaptchuk et al: Placebos without Deception: A Randomized Controlled Trial in Irritable Bowel Syndrome.
And for an overview of the whole issue, see this PLoS blog entry: Meet the Ethical Placebo: A Story that Heals.
Much of the latter blog entry is about clinical (not research) use of placebos. But still, it’s something those of us with an interest in Research Ethics need to think about. As knowledge grows about the size, limits, and exact mechanism behind the placebo effect, we may well need to rethink the role of placebos in randomized controlled trials.