title: Design characteristic of randomised controlled trials for geographic atrophy in age-related macular degeneration: selection of outcomes and sample size calculation.
abstract: OBJECTIVE
  The selection of suitable outcomes and sample size calculation are critical factors in the design of a randomised controlled trial (RCT). The goal of this study was to identify the range of outcomes and information on sample size calculation in RCTs on geographic atrophy (GA).
  
  
  METHODS
  We carried out a systematic review of age-related macular degeneration (AMD) RCTs. We searched MEDLINE, EMBASE, Scopus, Cochrane Library, www.controlled-trials.com, and www.ClinicalTrials.gov. Two independent reviewers screened records. One reviewer collected data and the second reviewer appraised 10% of collected data. We scanned references lists of selected papers to include other relevant RCTs.
  
  
  RESULTS
  Literature and registry search identified 3816 abstracts of journal articles and 493 records from trial registries. From a total of 177 RCTs on all types of AMD, 23 RCTs on GA were included. Eighty-one clinical outcomes were identified. Visual acuity (VA) was the most frequently used outcome, presented in 18 out of 23 RCTs and followed by the measures of lesion area. For sample size analysis, 8 GA RCTs were included. None of them provided sufficient Information on sample size calculations.
  
  
  CONCLUSIONS
  This systematic review illustrates a lack of standardisation in terms of outcome reporting in GA trials and issues regarding sample size calculation. These limitations significantly hamper attempts to compare outcomes across studies and also perform meta-analyses.
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK.
authors.forename: A K
authors.initials: AK
authors.lastname: Krezel
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK.
authors.forename: R E
authors.initials: RE
authors.lastname: Hogg
authors.affiliation: Former student of Queen's University Belfast, Belfast, UK.
authors.forename: S
authors.initials: S
authors.lastname: Krezel
authors.affiliation: Medical Library, Queen's University Belfast, Belfast, UK.
authors.forename: R
authors.initials: R
authors.lastname: Fallis
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK.
authors.forename: A
authors.initials: A
authors.lastname: Azuara-Blanco
mesh_terms: D057092:Geographic Atrophy / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D017063:Outcome Assessment, Health Care; D016032:Randomized Controlled Trials as Topic; D012107:Research Design; D018401:Sample Size; D011795:Surveys and Questionnaires