Many people have accepted the idea that taking a placebo—for example, a pill with no active medicine in it—can have powerful effects on the body. The reality is quite different, according to the authors of a Perspective published today by the Medical Journal of Australia.
A placebo is designed to look, taste, smell and feel like a real treatment; but it does not contain the active ingredient. Examples include a sugar pill, salt water (saline) or a fake surgical procedure.
Placebos have entered popular culture. A good example is the famous MAS*H television series episode in which the doctors give the patients placebo capsules filled with the sugar scraped off doughnuts when the supply of morphine runs out.
Professor Christopher Maher, director of the Institute for Musculoskeletal Health at the University of Sydney, and colleagues wrote that recent commentaries in major medical journals advocating for placebos in clinical care are based on deeply flawed studies.
“Given the recent advocacy for the clinical use of placebos, it is timely to consider the evidence underpinning these claims,” Maher and colleagues wrote.
The authors examined the evidence for recent claims such as:
“Placebos provide important treatment effects”—”reviews that appropriately measure the placebo effect show that placebos usually only have modest effects”;
“The color and shape of a placebo pill influences the size of the placebo effect”—”this idea has mainly come from studies where participants did not have a health condition or even take the placebo pill. The studies simply asked people what pill they thought might work best. And even these flawed studies yielded inconsistent results”;
“Placebos, even when honestly described as inert, create important clinical effects”—”These claims are based upon doubtful science. For example, one study that supposedly supports this idea completely ignored the data for the control group.”; and,
“Placebos are getting more effective over time”—”it is impossible to manipulate time in a clinical trial so this claim has no basis.”
Maher and colleagues wrote that the above claims were examples of “how much of the current discourse on placebo seems to focus more on enshrining placebos as mysterious and powerful and less on making a practical difference to patient care and outcomes.”
“We know from reviews of the clinical trial evidence that a placebo will provide a small effect, but the real treatment will normally provide better outcomes for the patient. “
“It would be better to dismiss placebos and instead manage patients with real evidence-based treatments.”