title: Reliability of phenotypic early-onset ataxia assessment: a pilot study.
abstract: OBJECTIVE
  To investigate the interobserver agreement on phenotypic early-onset ataxia (EOA) assessment and to explore whether the Scale for Assessment and Rating of Ataxia (SARA) could provide a supportive marker.
  
  
  METHODS
  Seven movement disorder specialists provided independent phenotypic assessments of potentially ataxic motor behaviour in 40 patients (mean age 15y [range 5-34]; data derived from University Medical Center Groningen medical records 1998-2012). We determined interobserver agreement by Fleiss' kappa. Furthermore, we compared percentage SARA subscores ([subscore/total score]×100%) between 'indisputable' (primary ataxia recognition by at least six observers) and 'mixed' (ataxia recognition, unfulfilling 'indisputable' criteria) EOA phenotypes.
  
  
  RESULTS
  Agreement on phenotypic EOA assessment was statistically significant (p<0.001), but of moderate strength (Fleiss' kappa=0.45; 95% CI 0.38-0.51). During mild disease progression, percentage SARA gait subscores discriminated between 'indisputable' and 'mixed' EOA phenotypes. In patients with percentage SARA gait subscores >30%, primary ataxia was more frequently present than in those with subscores <30% (p=0.001).
  
  
  CONCLUSIONS
  Among movement-disorder professionals from different disciplines, interobserver agreement on phenotypic EOA recognition is of limited strength. SARA gait subscores can provide a supportive discriminative marker between EOA phenotypes. Hopefully, future phenotypic insight will contribute to the inclusion of uniform, high-quality data in international EOA databases.
authors.affiliation: Department of Neurology, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Tjitske F
authors.initials: TF
authors.lastname: Lawerman
authors.affiliation: Department of Neurology, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Rick
authors.initials: R
authors.lastname: Brandsma
authors.affiliation: Department of Neurology, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Joke T
authors.initials: JT
authors.lastname: van Geffen
authors.affiliation: Department of Neurology, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Roelineke J
authors.initials: RJ
authors.lastname: Lunsing
authors.affiliation: General Practice, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Huibert
authors.initials: H
authors.lastname: Burger
authors.affiliation: Department of Neurology, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Marina A J
authors.initials: MA
authors.lastname: Tijssen
authors.affiliation: Department of Neurology, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: de Vries
authors.affiliation: Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Tom J
authors.initials: TJ
authors.lastname: de Koning
authors.affiliation: Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Sival
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001259:Ataxia / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D006801:Humans; D010641:Phenotype; D010865:Pilot Projects; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D055815:Young Adult