July 22, 2011
The Power of Placebo
We’ve all heard of the power of the placebo effect – the benefit from receiving an inactive medication or a phony simulated treatment. But how do placebos work? Do they improve objective measures of disease? Do they improve the patient’s subjective symptoms? Do they do both? A cleverly designed study in last week’s New England Journal of Medicine (link 1 below) answers that question.
The investigators chose asthma as the disease in which to study the effect of placebo because asthma can cause uncomfortable symptoms – wheezing, breathlessness – but can also be assessed objectively through lung function tests. The study enrolled patients with stable mild or moderate asthma. Each patient attended treatment sessions on 12 different days in which they received one of four treatments, so they received each treatment three different times.
One treatment was an albuterol inhaler. Albuterol is the standard medication for rapid airway dilation and is very commonly used by asthma patients. The second treatment was an inhaler with no active medication. Patients taking either the albuterol or placebo inhalers were not informed about the contents of the inhaler, and neither were the investigators monitoring them.
The third treatment was sham acupuncture. Sham acupuncture looks to the patient as if needles are being inserted in his skin, just as in traditional acupuncture. The patient also feels the needle poke. But the needle actually retracts into a sleeve (like prop theater swords) and never penetrates the skin.
The fourth treatment was no intervention. The patient was simply asked to wait a few hours before leaving.
Before and after each of the treatments the patients’ lung function was measured. After each of the treatments the patients were also asked to rate the improvement of their asthma symptoms.
The results were fairly dramatic.
The lung function tests improved substantially after albuterol, as expected, and didn’t improve significantly with the placebo inhaler, sham acupuncture or no intervention. But the patients’ perceived improvement did not match their lung function improvement. Patients reported no symptom improvement after a session of no intervention. They perceived significant symptom relief after albuterol, and they perceived equal symptom relief after the placebo inhaler and after sham acupuncture even though their lung functions did not improve with these interventions.
So the patients’ symptoms were relieved equally by any kind of perceived treatment, by what the authors of the study call “the ritual of treatment”. But lung function improved only with active medication.
What are we to learn from this? The authors of the study assert that this means that in diseases such as asthma we should be sure to follow objective disease measures, since the patients’ reports may lead us astray. An editorial in the same issue (2) disagrees and asserts that symptom relief is point of asthma treatment, not necessarily normalization of objective tests.
The right balance likely depends on the disease. Some diseases, like high blood pressure, have no symptoms. Objective tests have to be the benchmark of treatment. Other diseases, like migraines and fibromyalgia, have no objective findings. Clearly these must be treated with subjective symptom relief as the goal. Most illnesses are somewhere in between, and both active medication and the “ritual of treatment” have a valuable role.
(1) New England Journal of Medicine article: Active Albuterol or Placebo, Sham Acupuncture, or No Intervention in Asthma (full text by subscription only)
(2) New England Journal of Medicine editorial: Meaningful Placebos — Controlling the Uncontrollable (full text by subscription only)
Wall Street Journal Health Blog: The Placebo Effect, This Time in Asthma
Los Angeles Times Booster Shots: Asthma study reveals the power of the placebo effect
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