title: International development of the patient-reported outcome indices for multiple sclerosis (PRIMUS).
abstract: BACKGROUND
  The Patient-Reported Indices for Multiple Sclerosis (PRIMUS) comprises a suite of three scales for assessing symptoms, activity limitations, and quality of life in multiple sclerosis (MS). It was developed in the UK and has been shown to have excellent psychometric properties. This study describes the adaptation of eight language versions for Canadian English, Canadian French, French, German, Italian, Spanish, Swedish, and US English.
  
  
  METHODS
  The PRIMUS was translated using the dual-panel process. Cognitive debriefing interviews conducted with MS patients assessed face and content validity. Psychometric and scaling properties were assessed via a two-administration postal survey conducted in each country involving the PRIMUS, the Nottingham Health Profile (NHP), the Unidimensional Fatigue Impact Scale (U-FIS), and demographic questions.
  
  
  RESULTS
  Cognitive debriefing interviews demonstrated the acceptability of the new language versions. Analysis of survey data showed that the new language versions of the three PRIMUS scales were unidimensional (as indicated by fit to the Rasch model) and that they had good internal consistency and reproducibility. PRIMUS scale scores correlated as expected with those on the NHP and the U-FIS. The scales in all countries were able to discriminate between groups of patients on the basis of their self-reported MS severity, general health, and employment status.
  
  
  CONCLUSIONS
  The PRIMUS was successfully adapted into eight new languages. Most of the tests showed the PRIMUS to have good unidimensionality and to have good internal consistency, reproducibility, and construct validity. The measure is now available for use in clinical studies and trials involving these countries and the UK. Further work is required to assess the measure's responsiveness.
authors.affiliation: Galen Research, Manchester, UK. smckenna@galen-research.com
authors.forename: Stephen P
authors.initials: SP
authors.lastname: McKenna
authors.forename: Lynda C
authors.initials: LC
authors.lastname: Doward
authors.forename: James
authors.initials: J
authors.lastname: Twiss
authors.forename: Peter
authors.initials: P
authors.lastname: Hagell
authors.forename: Nadia C
authors.initials: NC
authors.lastname: Oprandi
authors.forename: John
authors.initials: J
authors.lastname: Fisk
authors.forename: François
authors.initials: F
authors.lastname: Grand'Maison
authors.forename: Virender
authors.initials: V
authors.lastname: Bhan
authors.forename: Txomin
authors.initials: T
authors.lastname: Arbizu
authors.forename: David
authors.initials: D
authors.lastname: Brassat
authors.forename: Thomas
authors.initials: T
authors.lastname: Kohlmann
authors.forename: David M
authors.initials: DM
authors.lastname: Meads
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Eckert
mesh_terms: D000328:Adult; D054521:Cultural Competency; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis*; D011788:Quality of Life; D015203:Reproducibility of Results; D057566:Self Report; D012720:Severity of Illness Index; D016896:Treatment Outcome