title: Item reduction based on rigorous methodological guidelines is necessary to maintain validity when shortening composite measurement scales.
abstract: OBJECTIVE
  To review current practice and update guidelines for the methodology of shortening composite measurement scales (CMSs).
  
  
  METHODS
  A literature review gathered data on 91 shortening processes from 1995 to 2009. The validity of the initial CMS, the shortening methods, and the validity of the derived short-form scales were examined. The results were compared with those from a previous literature review (articles from 1985 to 1995) to develop updated guidelines for CMS shortening.
  
  
  RESULTS
  The literature review revealed a persisting lack of use of rigorous methodology for CMS shortening. Of the 91 cases of CMS shortening, 36 combined a content approach and a statistical approach; 45 used only a statistical approach and 10 (11%) only a content approach. The updated guidelines deal with the validity and conceptual model of the initial CMS, the preservation of content and psychometric properties during shortening, the selection of items, and the validation of the short form.
  
  
  CONCLUSIONS
  Item reduction based on a rigorous methodology is necessary if the short-form instrument aims to maintain the validity and other measurement properties of the parent instrument, which in turn supports application in research and clinical practice.
authors.affiliation: Université Paris-Descartes, Sorbonne Paris Cité, Université de Lorraine, EA 4360 APEMAC Nancy, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Goetz
authors.forename: Joël
authors.initials: J
authors.lastname: Coste
authors.forename: Fabienne
authors.initials: F
authors.lastname: Lemetayer
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Rat
authors.forename: Sébastien
authors.initials: S
authors.lastname: Montel
authors.forename: Sophie
authors.initials: S
authors.lastname: Recchia
authors.forename: Marc
authors.initials: M
authors.lastname: Debouverie
authors.forename: Jacques
authors.initials: J
authors.lastname: Pouchot
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Spitz
authors.forename: Francis
authors.initials: F
authors.lastname: Guillemin
mesh_terms: D003625:Data Collection / Q000379:methods* / Q000592:standards*; D004812:Epidemiologic Methods; D017408:Guidelines as Topic; D006801:Humans; D011594:Psychometrics / Q000592:standards; D015203:Reproducibility of Results; D012107:Research Design / Q000592:standards*; D013223:Statistics as Topic