title: Meta-analysis of the placebo response in ulcerative colitis.
abstract: OBJECTIVE
  The placebo response rate in randomized controlled trials (RCTs) in ulcerative colitis (UC) varies from 0 to 76%. The aims of this study were to quantify the pooled placebo response rate and identify the factors affecting it.
  
  
  METHODS
  We performed a meta-analysis of 110 RCTs carried out between 1955 and 2005 and published in English. Regression analysis was used to identify factors significantly modifying placebo response.
  
  
  RESULTS
  The pooled placebo remission rate was 23% (95%CI: 18.4-28%) and the pooled placebo improvement rate was 32.1% (95%CI: 28.1-36.3%). Multivariate analysis showed that the country where the study was performed (P = 0.025 for placebo remission and P = 0.0083 for placebo response rates) significantly influenced the placebo remission and response rates.
  
  
  CONCLUSIONS
  Placebo remission and response rates in RCTs of UC are highly variable and are significantly influenced by the country in which the RCT is performed.
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center, 300 Deaconess Building, 1 Deaconess Road, Boston, MA 02215, USA. sgarud@bidmc.harvard.edu
authors.forename: Sagar
authors.initials: S
authors.lastname: Garud
authors.forename: Alphonso
authors.initials: A
authors.lastname: Brown
authors.forename: Adam
authors.initials: A
authors.lastname: Cheifetz
authors.forename: Emily B
authors.initials: EB
authors.lastname: Levitan
authors.forename: Ciaran P
authors.initials: CP
authors.lastname: Kelly
mesh_terms: D003093:Colitis, Ulcerative / Q000628:therapy*; D006801:Humans; D015990:Placebo Effect; D016032:Randomized Controlled Trials as Topic; D012074:Remission Induction