Reliability of the Burke-Fahn-Marsden scale in a multicenter trial for dystonia

Pierre Krystkowiak, Sophie Tezenas du Montcel, Laurent Vercueil, Jean-Luc Houeto, Christelle Lagrange, Philippe Cornu, Serge Blond, Alim-Louis Benabid, Pierre Pollak, Marie Vidailhet,
Mov Disord.. 2007-01-01; 22(5): 685-689
DOI: 10.1002/mds.21392

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1. Mov Disord. 2007 Apr 15;22(5):685-9. doi: 10.1002/mds.21392.

Reliability of the Burke-Fahn-Marsden scale in a multicenter trial for dystonia.

Krystkowiak P(1), du Montcel ST, Vercueil L, Houeto JL, Lagrange C, Cornu P,
Blond S, Benabid AL, Pollak P, Vidailhet M; SPIDY Group.

Author information:
(1)Department of Neurology and Movement Disorders, Lille University Medical
Center, Lille, France.

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.
PURPOSE: 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.
CONCLUSION: 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.

DOI: 10.1002/mds.21392
PMID: 17274034 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus