title: Content and criterion validity of the preliminary core dataset for clinical trials in fibromyalgia syndrome.
abstract: OBJECTIVE
  Increasing research interest and emerging new therapies for treatment of fibromyalgia (FM) have led to a need to develop a consensus on a core set of outcome measures that should be assessed and reported in all clinical trials, to facilitate interpretation of the data and understanding of the disease. This aligns with the key objective of the Outcome Measures in Rheumatology (OMERACT) initiative to improve outcome measurement through a data driven, interactive consensus process.
  
  
  METHODS
  Through patient focus groups and Delphi processes, working groups at previous OMERACT meetings identified potential domains to be included in the core data set. A systematic review has shown that instruments measuring these domains are available and are at least moderately sensitive to change. Most instruments have been validated in multiple languages. This pooled analysis study aims to develop the core data set by analyzing data from 10 randomized controlled trials (RCT) in FM.
  
  
  RESULTS
  Results from this study provide support for the inclusion of the following in the core data set: pain, tenderness, fatigue, sleep, patient global assessment, and multidimensional function/health related quality of life. Construct validity was demonstrated with outcome instruments showing convergent and divergent validity. Content and criterion validity were confirmed by multivariate analysis showing R square values between 0.4 and 0.6. Low R square value is associated with studies in which one or more domains were not assessed.
  
  
  CONCLUSIONS
  The core data set was supported by high consensus among attendees at OMERACT 9. Establishing an international standard for RCT in FM should facilitate future metaanalyses and indirect comparisons.
authors.affiliation: Sir Alfred Baring Garrod Clinical Trials Unit, Academic Department Rheumatology, Weston Education Centre, King's College London, Cutcombe Road, London, SE5 9RJ UK. ernest.choy@kcl.ac.uk
authors.forename: Ernest H
authors.initials: EH
authors.lastname: Choy
authors.forename: Lesley M
authors.initials: LM
authors.lastname: Arnold
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Clauw
authors.forename: Leslie J
authors.initials: LJ
authors.lastname: Crofford
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Glass
authors.forename: Lee S
authors.initials: LS
authors.lastname: Simon
authors.forename: Susan A
authors.initials: SA
authors.lastname: Martin
authors.forename: C Vibeke
authors.initials: CV
authors.lastname: Strand
authors.forename: David A
authors.initials: DA
authors.lastname: Williams
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Mease
mesh_terms: D003072:Cognition Disorders / Q000503:physiopathology; D032921:Consensus; D003697:Delphi Technique; D005221:Fatigue / Q000503:physiopathology; D005356:Fibromyalgia / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D006801:Humans; D007391:International Cooperation; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000592:standards*; D010146:Pain / Q000503:physiopathology; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D015203:Reproducibility of Results; D013577:Syndrome