title: Quantitative analysis of placebo response and factors associated with menopausal hot flashes.
abstract: OBJECTIVE
  The aim of the study was to quantitatively analyze the placebo response and the factors associated with menopausal hot flashes.
  
  
  METHODS
  The PubMed and Cochrane Library databases were searched for placebo-controlled trials that reported the treatment of menopausal hot flashes, with a retrieval deadline of December 31, 2015. The clinical and demographic characteristics of participants and placebo responses, defined as the percentage of reduction in hot flashes at each observation time point compared with that of baseline values, were extracted from the studies. Model-based meta-analysis was used to describe the time course of placebo response and identify the related factors.
  
  
  RESULTS
  Eighty-five trials in 78 articles, involving 8,302 women, were included in the analysis. Of these, 47 trials were about hormonal drugs, 37 were about nonhormonal drugs, and 1 included both hormonal and nonhormonal drugs. Our results indicated that the placebo responses for hot flashes increased in a time-dependent manner and reached a plateau after week 12. Additionally, the placebo responses were significantly higher in the trials of hormonal drugs than in the trials of nonhormonal drugs at week 24 (-51.2% vs -40.4%; P < 0.05), and the difference between them was comparable with the effect of paroxetine.
  
  
  CONCLUSIONS
  The placebo response for menopausal hot flashes was related to the active comparator; a higher response rate was observed in trials of hormonal drugs than in trials of nonhormonal drugs. These findings suggest that subjective expectations affect the treatment efficacy of menopausal hot flashes.
authors.affiliation: Center for Drug Clinical Research, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Lujin
authors.initials: L
authors.lastname: Li
authors.forename: Ling
authors.initials: L
authors.lastname: Xu
authors.forename: Junyi
authors.initials: J
authors.lastname: Wu
authors.forename: Lidan
authors.initials: L
authors.lastname: Dong
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Lv
authors.forename: Qingshan
authors.initials: Q
authors.lastname: Zheng
mesh_terms: D000928:Antidepressive Agents / Q000627:therapeutic use; D015914:Estrogen Replacement Therapy; D005260:Female; D019584:Hot Flashes / Q000188:drug therapy*; D006801:Humans; D008593:Menopause; D015990:Placebo Effect; D016896:Treatment Outcome
chemical_list: D000928:Antidepressive Agents