The placebo effect has long been of interest to skeptics for its presumed role in alternative medicine. The Skeptics’ Dictionary (http://www.skepdic.com) has a lengthy entry, describing a placebo as an inert substance, or fake surgery or therapy, used as a control in an experiment or given to a patient for its probable beneficial effect. It goes on to add the effect has at least three components.
The first is psychological, due either to a real effect caused by belief, or to a subjective delusion – “if I believe the pill will help, then it will help.” Alternatively, the effect may be largely illusory – an illness or injury will often get better by itself, whether it is treated or not.
As a third alternative, the process of treatment, involving attention, care, and affection may itself trigger physical reactions in the body which promote healing, regardless of the nature of the treatment.
The second alternative has received a boost from a study published in May in the New England Journal of Medicine. Danish researchers Asbjorn Hrobjartsson and Peter C. Gotzsche performed a meta-study of 114 studies in which the experimental design included a genuine treatment, a placebo, and no treatment at all. In these studies, they found a slight effect of placebos on subjective outcomes, such as pain, reported by patients, but no significant effect on binary outcomes. Even the slightly positive subjective outcome result could be a reporting effect – patients want to please the doctor, so say they feel slightly better.
Reaction to the report has been mixed. Some researchers have said it confirms what they’d suspected all along, there is no placebo effect, it’s an illusion due to the simple fact that people often get better without treatment. Others argue that the metanalysis used is inappropriate for such a disparate group of studies. But however it turns out in the end, the affair raises some interesting points. One is the origin of the oft-repeated claim that, on average, a placebo effect will help 35% of patients. This has attained almost the status of an urban legend, but Hrobjartson eventually tracked its origin to a single 1955 paper in the Journal of the American Medical Association. Its author, Boston anaesthesiologist Henry Beecher, based his claim on a review of 12 studies, and, like other articles read by Hrobjartsson, it did not distinguish between the placebo effect and the natural course of the disease.
It’s hard to accept there is nothing to the placebo effect at all. There are reports of people developing addictions to placebos, or demonstrating adverse side effects, and trials showing patients with placebos do better than others simply left on waiting lists. But it’s a complex, multi-faceted phenomenon. If we are going to assert that an alternative health treatment is “just a placebo”, we need to be careful about what we mean by that. Does it mean the patient is experiencing a subjective delusion, or genuine healing through care and support, or simply going through the natural course of an illness? The Danish study won’t be the last word on this subject, but it has very nicely focused an issue which has had some very fuzzy edges.