Background: Information that enhances expectations about drug effectiveness improves the response to placebos for pain. Although asthma symptoms often improve with placebo, it is not known whether the response to placebo or active treatment can be augmented by increasing expectation of benefit.
Objective: The study objective was to determine whether response to placebo or a leukotriene antagonist (montelukast) can be augmented by messages that increase expectation of benefit.
Methods: A randomized 20-center controlled trial enrolled 601 asthmatic patients with poor symptom control who were assigned to one of 5 study groups. Participants were randomly assigned to one of 4 treatment groups in a factorial design (ie, placebo with enhanced messages, placebo with neutral messages, montelukast with enhanced messages, or montelukast with neutral messages) or to usual care. Assignment to study drug was double masked, assignment to message content was single masked, and usual care was not masked. The enhanced message aimed to increase expectation of benefit from the drug. The primary outcome was mean change in daily peak flow over 4 weeks. Secondary outcomes included lung function and asthma symptom control.
Results: Peak flow and other lung function measures were not improved in participants assigned to the enhanced message groups versus the neutral messages groups for either montelukast or placebo; no differences were noted between the neutral placebo and usual care groups. Placebo-treated participants had improved asthma control with the enhanced message but not montelukast-treated participants; the neutral placebo group did have improved asthma control compared with the usual care group after adjusting for baseline difference. Headaches were more common in participants provided messages that mentioned headache as a montelukast side effect.
Conclusions: Optimistic drug presentation augments the placebo effect for patient-reported outcomes (asthma control) but not lung function. However, the effect of montelukast was not enhanced by optimistic messages regarding treatment effectiveness.
Trial registration: ClinicalTrials.gov NCT00148408.