Placebo improvement in pharmacologic treatment of menopausal hot flashes: time course, duration, and predictors

To characterize the time course, duration of improvement, and clinical predictors of placebo response in treatment of menopausal hot flashes.

Data were pooled from two trials conducted in the Menopausal Strategies: Finding Lasting Answers to Symptoms and Health network, providing a combined placebo group (n = 247) and a combined active treatment group (n = 297). Participants recorded hot flash frequency in diaries twice daily during treatment (Weeks 0-8) and subsequent follow-up (Weeks 9-11). The primary outcome variable was clinically significant improvement, defined as a 50% or greater decrease in hot flash frequency from baseline and calculated for each week in the study. Subgroups were defined a priori using standard clinical definitions for significant improvement and partial improvement. Clinical and demographic characteristics of the participants were evaluated as predictors of improvement.

Clinically significant improvement with placebo accrued each treatment week, with 33% significantly improved at Week 8. Of placebo responders who were improved at both Weeks 4 and 8, 77% remained clinically improved at Week 11 after treatment ended. Independent predictors of significant placebo improvement in the final multivariable model were African American race (odds ratio [OR] = 5.61, 95% confidence interval [CI] = 2.41-13.07, p < .001), current smokers (OR = 2.30, 95% CI = 1.05-5.06, p = .038), and hot flash severity in screening (OR = 1.45, 95% CI = 1.00-2.10, p = .047).

Clinically significant improvement with placebo accrued throughout treatment with a time course similar to improvement with active drug. A meaningful number of participants in the placebo group sustained a clinically significant response after stopping placebo pills. The results suggest that nonspecific effects are important components of treatment and warrant further studies to optimize their contributions in clinical care.