Placebo effect may not exist

Study authors Asbjorn Hrobjartsson and Peter C. Gotzsche looked at 114 clinical trials - covering 7,500 patients with 40 different clinical conditions - in which patients were randomly assigned to placebo or no treatment. For the purposes of the study, the placebo could be "pharmacologic (e.g., a tablet), physical (e.g., a manipulation) or psychological (e.g., a conversation)." The authors found that "as compared with no treatment, placebo had no significant effect on binary outcomes, regardless of whether these outcomes were subjective or objective."

Concluded the researchers: "We found little evidence in general that placebos had powerful clinical effects. Although placebos had no significant effects on objective or binary outcomes, they had possible small benefits in studies with continuous subjective outcomes and for the treatment of pain. Outside the setting of clinical trials, there is no justification for the use of placebos."

In an editorial in the same issue of the journal, John C. Bailar of the University of Chicago wrote, "Overall, the uncompromising condemnation of placebos advocated by Hrobjartsson and Gotzsche seems to me just a bit too sweeping.

"In particular," he continued, "the evidence that placebos might contribute to pain relief may merit their continued therapeutic use when there is reason to think that a patient may benefit. … However, I believe there should be a sharp reduction in the prescription of placebos and careful justification for each continued use. Future studies may show either that placebos have benefits not yet documented or that the appearance of small benefits - for example, for pain relief - is, in fact, illusory. At present, I would not want to prescribe or receive a placebo without some reason that was far more specific than weak evidence of some general 'placebo effect.'" PR