title: The placebo effect in early-phase glaucoma clinical trials.
abstract: OBJECTIVE
  To analyze the extent and prevalence of the placebo effect in prior early-phase glaucoma clinical studies.
  
  
  METHODS
  Articles were evaluated on phase I and II trials of glaucoma medicines that became commercially available after 1977 with a placebo arm that involved glaucoma patients.
  
  
  RESULTS
  We included 23 studies with 23 treatment arms with a total of 1703 patients in articles evaluating 10 different glaucoma medications. This study showed that at 8 AM (n = 18), the average decrease in placebo from untreated baseline was 2.3 ± 1.6 mm Hg (9%), while for the diurnal curve (n = 17), the mean decrease was 1.4 ± 1.1 mm Hg (6%). At 8 AM, 8/18 treatment arms had greater than 2 mm Hg intraocular pressure (IOP) decrease, and all had at least some reduction in IOP. For the diurnal curve, 4 of 17 studies had reduced IOP greater than 2 mm Hg. One treatment arm had no placebo effect.
  
  
  CONCLUSIONS
  This study suggests that a placebo effect is common in glaucoma clinical trials and potentially could limit the ability to evaluate the efficacy of a new medicine.
authors.affiliation: Department of Ophthalmology, Medical University of South Carolina , Charleston, SC , USA and.
authors.forename: R Allan
authors.initials: RA
authors.lastname: Sharpe
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Nelson
authors.forename: Jeanette A
authors.initials: JA
authors.lastname: Stewart
authors.forename: William C
authors.initials: WC
authors.lastname: Stewart
mesh_terms: D000959:Antihypertensive Agents / Q000008:administration & dosage*; D002940:Circadian Rhythm / Q000502:physiology*; D002986:Clinical Trials as Topic; D005901:Glaucoma / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects* / Q000502:physiology
chemical_list: D000959:Antihypertensive Agents
keywords: Clinical studies; glaucoma; phase; placebo effect