Do Placebos Work Even When Patients Know They are Placebos?
It’s commonly known across all fields of medicine, psychiatry included, that in clinical trials, placebo treatment works, in some cases just as well as “real” treatment. (See for example, Fulda S and Wetter TC, Brain 2008;131(4):902–917). But most of our knowledge about placebos is from blinded trials—that is, ones where participants, and ideally researchers, don’t know who gets the real treatment and who gets the placebo. Recently, researchers conducted a study in which patients were explicitly told they were taking a placebo to see if it still could result in improved outcomes.
In this study of 80 people with irritable bowel syndrome (IBS), participants were randomly assigned to one of two groups: one received a sugar pill (n=37), the other, no treatment (n=43). The researchers presented the placebo with what they called “persuasive rationale”— telling patients that although it was just a sugar pill, in previous studies it improved symptoms through “significant mindbody self-healing processes.” Both groups received educational visits and/or physician exams at day one, day 11, and day 21. According to researchers, “all visits were in the context of a warm supportive patient-practitioner relationship.”
Patients in the “aware of placebo” group had statistically significantly greater scores on the main outcome measure (IBS global improvement scale (IBS-GIS)) at both the midpoint and the end of the trial—placebo patients finished with a five point improvement vs a 3.9 point improvement for the no treatment group (Kaptchuk TJ et al, PLoS ONE 2010;5(12):e15591).
TCPR’s Take: At first glance, this study appears to show that placebos are effective even when patients realize they are simply placebos. However, some methodological quirks of this trial should temper our confidence in the results. First, there may have been a selection bias, considering participants were recruited with an ad for a “mind-body study.” Such patients may have been particularly prone to believe in the power of placebo. Second, one could argue that, by repeatedly telling people that the sugar pill had been effective, the researchers biased the study in favor of the placebo effect. The ethics of giving patients placebos as treatment remains in dispute, with many medical organizations recommending against the practice. But, bottom line, if you decide to offer your patients placebo treatment, this study shows that a convincing sales pitch might significantly improve the results.