Type of Placebo Matters in Trials of Migraine Prophylaxis

October 16, 2013

By Megan Brooks

NEW YORK (Reuters Health) Oct 16 - Different placebos have different effects in trials of migraine prophylaxis, a meta-analytic review shows.

Physical placebo treatments (sham surgery and sham acupuncture) yield greater placebo effects than oral placebo treatments, the study found.

Based on the results, said lead author Dr. Karin Meissner in an email, doctors who treat patients with migraine "should be aware that a relevant part of the overall effect they observe in practice might be the result of a placebo effect and that the size of such effects might differ between treatment modalities. Interventions that entail a more elaborate and impressive treatment ritual, a higher level of attention as well as physical contact are more likely to enhance the overall treatment effect, and thus the benefit for the patient by inducing a large placebo effect."

"Since we know today that placebo effects are not imaginary, but real neurobiological phenomena, physicians should not be afraid to try to harness placebo effects and to communicate this benefit to their patients. While the study focused on migraine only, the same conclusion could well be true for other conditions in which psychological factors play a role," Dr. Meissner said.

In an Editor's note published with the study online October 14 in JAMA Internal Medicine, Dr. Rita Redberg of University of California San Francisco writes, "The importance of the placebo effect is well known and the use of the placebo in medicine dates back several centuries."

"In evaluating therapy for migraine prophylaxis, we learn from this review that like treatments should be compared, such as surgery treatment with sham surgery treatment and pill with sham pill. This important lesson extends far beyond migraine prophylaxis treatment," Dr. Redberg says.

The analysis, by Dr. Meissner from the Institute of Medical Psychology, Ludwig-Maximillians University in Munich, Germany, and colleagues, included 79 randomized trials assessing migraine prophylaxis. All had an observation period of at least eight weeks after randomization and compared an experimental treatment with a placebo control group.

They found that the amount of reduction in migraine frequency varied systematically between different types of placebo.

The sham acupuncture and sham surgery were associated with a more pronounced reduction of migraine frequency than oral pharmacological placebos and were the only significant predictors of response in placebo groups in multivariable analyses (p=0.005 and p=0.001, respectively).

Network meta-analysis confirmed that more patients reported response in sham acupuncture groups than in oral pharmacological placebo groups (odds ratio, 1.88). Sham surgery also appeared to be more effective in this analysis, but data were limited, they note.

"Oral placebos for herbs, vitamins, or homeopathic drugs; injected placebos for pharmacological drugs; a sham electromagnetic device; and sham cognitive-behavioral treatment were associated with effects similar to oral pharmacological placebos," they note.

"Although our study cannot prove that this association is causal, the results support the notion that some placebo treatments can trigger clinically relevant responses," the authors say.

In her email to Reuters Health, Dr. Meissner wrote, "Migraine is a chronic pain condition, which is known to be influenced by psychological factors. Therefore, it is not surprising that placebo interventions affect the course of migraine, e.g. by reducing the frequency of migraine attacks."

Continuing, she said, "Our study now shows that different placebo interventions in clinical trials are not equally effective in reducing migraine attacks. More impressive placebo interventions, such as sham acupuncture and sham surgery, were associated with larger effects than orally prescribed placebo pills. Even though acupuncture is associated with a smaller specific effect when compared to its placebo than are oral pharmacological drugs, the total improvement after sham surgery and sham acupuncture is as large as after active drugs."

The study was supported by the German Ministry of Education and Research. The authors have no relevant disclosures.

SOURCES: http://bit.ly/19N0Hln and http://bit.ly/19N0Hln

JAMA Intern Med 2013.

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