Objective: Although not well-understood, dermatologic diseases studied in clinical trials often demonstrate substantial response to placebo. The study objective is to determine if optimism, public self-consciousness and other personality traits predict response to placebo or active treatment in a dermatology clinical trial.
Methods: A questionnaire was mailed to subjects previously enrolled in a two-center rosacea study who had been randomized to either a treatment or placebo gel. The questionnaire included the Revised Life Orientation Test (LOT-R), the Public Self-Consciousness Scale, and questions to assess personality traits.
Results: Forty-seven subjects out of 83 (57%) returned the questionnaire. There was no statistically significant difference in the LOT-R score in those who responded to placebo versus those who did not (18.08 vs 17.92, P =0.92) nor in those who responded to active treatment versus those who did not (16.27 vs 15.86, P =0.79). There was no statistically sigificant difference in public-self consciousness among placebo or active treatment responders versus non-responders (11.75 vs 10.67, P =0.66; 13.55 vs 14.45, P =0.68). The placebo responders were more likely to report that they were not unusually sensitive to most drugs/medications (X2= 8.33, P =0.004).
Conclusion: Although this pilot study is small, there was no meaningful difference in levels of optimism or public self-consciousness among those who responded to placebo. Placebo responders were more likely to report that they were not sensitive to most drugs/medications, raising the possibility that they are actually less likely to detect when they are on medications.