Reliability and validity of the International Cooperative Ataxia Rating Scale: a study in 156 spinocerebellar ataxia patients

Tanja Schmitz-Hübsch, Sophie Tezenas du Montcel, Laszlo Baliko, Sylvia Boesch, Sara Bonato, Roberto Fancellu, Paola Giunti, Christoph Globas, Jun-Suk Kang, Berry Kremer, Caterina Mariotti, Bela Melegh, Maryla Rakowicz, Rafal Rola, Sylvie Romano, Lodger Schöls, Sandra Szymanski, Bart P C van de Warrenburg, Elzbieta Zdzienicka, Alexandra DürrThomas Klockgether

Research output: Contribution to journalArticleAcademicpeer-review

134 Citations (Scopus)


To evaluate the efficacy of treatments in spinocerebellar ataxias (SCAs), appropriate clinical scales are required. This study evaluated metric properties of the International Cooperative Ataxia Rating Scale (ICARS) in 156 SCA patients and 8 controls. ICARS was found to be a reliable scale satisfying accepted criteria for interrater reliability, test-retest reliability, and internal consistency. Although validity testing was limited, we found evidence of validity of ICARS when ataxia disease stages and Barthel index were used as external criteria. On the other hand, our study revealed two major problems associated with the use of ICARS. First, the redundant and overlapping nature of several items gave rise to a considerable number of contradictory ratings. Second, a factorial analysis showed that the rating results were determined by four different factors that did not coincide with the ICARS subscales, thus questioning the justification of ICARS subscore analysis in clinical trials.

Original languageEnglish
Pages (from-to)699-704
Number of pages6
JournalMovement Disorders
Issue number5
Publication statusPublished - May-2006
Externally publishedYes


  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Disability Evaluation
  • Female
  • Humans
  • International Cooperation
  • Male
  • Middle Aged
  • Psychometrics
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Severity of Illness Index
  • Spinocerebellar Ataxias
  • Comparative Study
  • Journal Article
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

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