Non-concealed placebo treatment for menopausal hot flushes: Study protocol of a randomized-controlled trial.

Background: Beneficial effects of placebos are high in double-blind hot flush trials. Studies in various conditions suggest that honestly prescribed placebos may elicit symptom improvement.
Objective: To determine whether open label placebo (OLP) treatment is efficacious in alleviating hot flushes among peri- and postmenopausal women.
Methods/design: In this assessor-blinded, randomized-controlled trial, n = 100 women experiencing five or more daily hot flushes of at least moderate severity and bothersomeness are assigned 1:1 to a 4-week OLP treatment or no treatment. To explore the duration and maintenance of placebo effects, the OLP group is randomized a second time to either discontinue or continue the OLP treatment for another 4 weeks. All participants receive a briefing about placebo effects and study visits at baseline, post-treatment (4 weeks), and follow-up (8 weeks, OLP group only). Qualitative interviews about subjective experiences with the OLP treatment are conducted. Primary outcomes are differences between the OLP and the no-treatment group in the hot flush composite score (frequency × severity), and bothersomeness of hot flushes as assessed with the Hot Flush Rating Scale at post-treatment. Secondary outcomes include hot flush frequency, health-related quality of life, global improvement, and the number of responders at post-treatment. Data are analyzed by fitting (generalized) linear mixed models. An exploratory analysis of maintenance and duration is performed including follow-up data.
Discussion: This trial will contribute to the evaluation of OLP treatments in clinical practice and further our understanding about the magnitude of placebo effects in hot flush treatments.
Trial Registration: Clinicaltrials.gov, NCT03838523 . Retrospectively registered on February 12th, 2019. The first patient was enrolled on October 10th, 2018.