Patients with asthma could not tell the difference between placebo treatments and bona fide inhalers, even though an objective measure of lung capacity clearly distinguished active from inactive regimens. That is the result of a study led by pulmonologist Michael Wechsler, Brigham and Women’s Hospital, and placebo researcher Ted Kaptchuk, Beth Israel Deaconess Medical Center, both in Boston. Their paper was published in the July 14 issue of the New England Journal of Medicine.
What does this study have to do with pain? Placebo effects are powerful in pain, bedeviling clinical trials of new therapies and scuttling researchers’ ability to show therapeutic efficacy of active treatments. One message from the asthma study is that it may be necessary to assess responses in untreated patients—what the authors call “the control for the placebos”—to separate placebo effects, treatment effects, and natural changes in disease.
In the study, 39 patients each underwent four interventions: an albuterol inhaler (active treatment), a placebo inhaler, sham acupuncture, and no intervention. The interventions were administered on different visits, in random order. At each visit, responses were assessed by lung function testing and by patient reports on a visual analog scale of improvement. According to lung function, patients improved only with albuterol, and the two placebo interventions were not any better than no treatment. However, according to patients’ perceptions, the two placebos worked just as well as albuterol, and much better than no treatment.
Kaptchuk told PRF that he had thought the placebos might have some effect on lung function, given that previous asthma studies have shown improvement in placebo groups. However, those studies, he says, generally have not included no-treatment arms, so it was impossible to distinguish true placebo effects from the natural course of disease.
In their study, Wechsler and colleagues had to invent a metric for subjective asthma symptoms, since none existed. For pain, an objective measure is what is elusive. Even if pain researchers find such an index of pain—whether in the form of brain activity or some other biomarker—Kaptchuk says pain cannot be neatly separated into objective and subjective components.
Ultimately, Kaptchuk says, pain is about a patient’s experience, and the new findings underscore the capacity of placebos to modulate that experience. Whereas in asthma, there is reason to improve patients’ lung function even if they feel fine; in most cases of chronic pain, the thing that matters most is easing discomfort and disability. Does that mean that placebo is an underutilized weapon against pain?
In an accompanying editorial, Daniel Moerman, University of Michigan, Dearborn, implies as much. Treatments, even inactive ones, have meaning, he writes, and “maybe it is sufficient simply to show that a treatment yields significant improvement for the patients, has reasonable cost, and has no negative effects over the short or long term.”
