title: Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews.
abstract: BACKGROUND
  Our objective was to develop an instrument to assess the methodological quality of systematic reviews, building upon previous tools, empirical evidence and expert consensus.
  
  
  METHODS
  A 37-item assessment tool was formed by combining 1) the enhanced Overview Quality Assessment Questionnaire (OQAQ), 2) a checklist created by Sacks, and 3) three additional items recently judged to be of methodological importance. This tool was applied to 99 paper-based and 52 electronic systematic reviews. Exploratory factor analysis was used to identify underlying components. The results were considered by methodological experts using a nominal group technique aimed at item reduction and design of an assessment tool with face and content validity.
  
  
  RESULTS
  The factor analysis identified 11 components. From each component, one item was selected by the nominal group. The resulting instrument was judged to have face and content validity.
  
  
  CONCLUSIONS
  A measurement tool for the 'assessment of multiple systematic reviews' (AMSTAR) was developed. The tool consists of 11 items and has good face and content validity for measuring the methodological quality of systematic reviews. Additional studies are needed with a focus on the reproducibility and construct validity of AMSTAR, before strong recommendations can be made on its use.
authors.affiliation: EMGO Institute, VU University Medical Center, Amsterdam, The Netherlands. bshea@ciet.org
authors.forename: Beverley J
authors.initials: BJ
authors.lastname: Shea
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Grimshaw
authors.forename: George A
authors.initials: GA
authors.lastname: Wells
authors.forename: Maarten
authors.initials: M
authors.lastname: Boers
authors.forename: Neil
authors.initials: N
authors.lastname: Andersson
authors.forename: Candyce
authors.initials: C
authors.lastname: Hamel
authors.forename: Ashley C
authors.initials: AC
authors.lastname: Porter
authors.forename: Peter
authors.initials: P
authors.lastname: Tugwell
authors.forename: David
authors.initials: D
authors.lastname: Moher
authors.forename: Lex M
authors.initials: LM
authors.lastname: Bouter
mesh_terms: D015982:Bias; D005163:Factor Analysis, Statistical; D006801:Humans; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D012196:Review Literature as Topic; D011795:Surveys and Questionnaires