title: Choosing important health outcomes for comparative effectiveness research: a systematic review.
abstract: BACKGROUND
  A core outcome set (COS) is a standardised set of outcomes which should be measured and reported, as a minimum, in all effectiveness trials for a specific health area. This will allow results of studies to be compared, contrasted and combined as appropriate, as well as ensuring that all trials contribute usable information. The COMET (Core Outcome Measures for Effectiveness Trials) Initiative aims to support the development, reporting and adoption of COS. Central to this is a publically accessible online resource, populated with all available COS. The aim of the review we report here was to identify studies that sought to determine which outcomes or domains to measure in all clinical trials in a specific condition and to describe the methodological techniques used in these studies.
  
  
  METHODS
  We developed a multi-faceted search strategy for electronic databases (MEDLINE, SCOPUS, and Cochrane Methodology Register). We included studies that sought to determine which outcomes/domains to measure in all clinical trials in a specific condition.
  
  
  RESULTS
  A total of 250 reports relating to 198 studies were judged eligible for inclusion in the review. Studies covered various areas of health, most commonly cancer, rheumatology, neurology, heart and circulation, and dentistry and oral health. A variety of methods have been used to develop COS, including semi-structured discussion, unstructured group discussion, the Delphi Technique, Consensus Development Conference, surveys and Nominal Group Technique. The most common groups involved were clinical experts and non-clinical research experts. Thirty-one (16%) studies reported that the public had been involved in the process. The geographic locations of participants were predominantly North America (n = 164; 83%) and Europe (n = 150; 76%).
  
  
  CONCLUSIONS
  This systematic review identified many health areas where a COS has been developed, but also highlights important gaps. It is a further step towards a comprehensive, up-to-date database of COS. In addition, it shows the need for methodological guidance, including how to engage key stakeholder groups, particularly members of the public.
authors.affiliation: University of Liverpool, Department of Biostatistics, Liverpool, United Kingdom.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Gargon
authors.affiliation: University of Liverpool, Department of Biostatistics, Liverpool, United Kingdom.
authors.forename: Binu
authors.initials: B
authors.lastname: Gurung
authors.affiliation: University of Liverpool, Department of Biostatistics, Liverpool, United Kingdom.
authors.forename: Nancy
authors.initials: N
authors.lastname: Medley
authors.affiliation: University of Oxford, Centre for Statistics in Medicine, Botnar Research Centre, Oxford, United Kingdom.
authors.forename: Doug G
authors.initials: DG
authors.lastname: Altman
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Jane M
authors.initials: JM
authors.lastname: Blazeby
authors.affiliation: Queens University Belfast, Institute of Clinical Sciences, Block B, Royal Hospitals, Belfast, United Kingdom.
authors.forename: Mike
authors.initials: M
authors.lastname: Clarke
authors.affiliation: University of Liverpool, Department of Biostatistics, Liverpool, United Kingdom.
authors.forename: Paula R
authors.initials: PR
authors.lastname: Williamson
mesh_terms: D002986:Clinical Trials as Topic; D057186:Comparative Effectiveness Research / Q000379:methods*; D016206:Databases, Bibliographic; D005104:Expert Testimony; D006801:Humans; D016239:MEDLINE; D017063:Outcome Assessment, Health Care; D011639:Public Opinion