title: Reliability of the Burke-Fahn-Marsden scale in a multicenter trial for dystonia.
abstract: BACKGROUND
  The multicenter SPIDY trial (pallidal stimulation for generalized, idiopathic dystonia) recently reported a marked improvement in dystonia which was assessed by the Burke-Fahn-Marsden (BFM) scale. However, the reliability of this tool has rarely been evaluated and its use in a multicenter study has never been assessed prospectively.
  
  
  OBJECTIVE
  To evaluate the concordance between three unblinded clinical raters and one single-blinded rater for 10 prospective series of ratings on the BFM scale in 22 dystonic patients of the SPIDY study.
  
  
  METHODS
  Ten assessments on the BFM scale were performed under various stimulation conditions at different time points (before surgery and 1, 3, 6, and 12 months afterwards). Patients were first evaluated by three unblinded clinical raters (one per center). All assessments were videotaped and sent to a blinded rater. Intra- and inter-rater reliability was assessed using intraclass correlation coefficients.
  
  
  RESULTS
  The intra-rater reliability at inclusion was better for the blinded rater than for the clinical raters. The inter-rater reliability (comparing the blinded rater with each clinical rater) was "very good" at inclusion, "fair" at month 1 and was "good" at month 3, month 6, and month 12.
  
  
  CONCLUSIONS
  Blinding (rather than video) is probably the key factor in better intra-rater reliability and can produce more accurate rating than clinical rating. Consequently, a blind procedure should be performed systematically in multicenter studies. As inter-rater reliability is good in trained unblinded raters, the BFM scale may also be used in the follow up of dystonic patients in movement disorders centers, in clinical practice.
authors.affiliation: Department of Neurology and Movement Disorders, Lille University Medical Center, Lille, France. p-krystkowiak@chru-lille.fr
authors.forename: Pierre
authors.initials: P
authors.lastname: Krystkowiak
authors.forename: Sophie Tezenas
authors.initials: ST
authors.lastname: du Montcel
authors.forename: Laurent
authors.initials: L
authors.lastname: Vercueil
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Houeto
authors.forename: Christelle
authors.initials: C
authors.lastname: Lagrange
authors.forename: Philippe
authors.initials: P
authors.lastname: Cornu
authors.forename: Serge
authors.initials: S
authors.lastname: Blond
authors.forename: Alim-Louis
authors.initials: AL
authors.lastname: Benabid
authors.forename: Pierre
authors.initials: P
authors.lastname: Pollak
authors.forename: Marie
authors.initials: M
authors.lastname: Vidailhet
mesh_terms: D000293:Adolescent; D000328:Adult; D046690:Deep Brain Stimulation / Q000379:methods*; D004421:Dystonia / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D005500:Follow-Up Studies; D005917:Globus Pallidus / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination / Q000706:statistics & numerical data*; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D013223:Statistics as Topic