Reliability of phenotypic early-onset ataxia assessment: A pilot study

Research output: Contribution to journalArticle


Aim: 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. Method: 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). Interpretation: 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.


  • Tjitske F. Lawerman
  • Rick Brandsma
  • Joke T. van Geffen
  • Roelineke J. Lunsing
  • Huibert Burger
  • Marina A.J. Tijssen
  • Jeroen J. de Vries
  • Tom J. de Koning
  • Deborah A. Sival
External organisations
  • Beatrix Children's Hospital
  • University of Groningen
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Neurology
Original languageEnglish
Pages (from-to)70-76
Number of pages7
JournalDevelopmental Medicine and Child Neurology
Issue number1
Publication statusPublished - 2016 Jan 1
Publication categoryResearch
Externally publishedYes