Inter-rater reliability of the International Cooperative Ataxia Rating Scale (ICARS)

Mov Disord. 2004 Feb;19(2):190-2. doi: 10.1002/mds.10657.


We assessed the inter-rater reliability of the 100-point International Cooperative Ataxia Rating Scale (ICARS). Three neurologists independently rated videotaped ICARS examinations of 22 subjects with genetically determined ataxias (spinocerebellar ataxia [SCA] Type 1 in 11; SCA Type 2 in 1; Friedreich's ataxia in 10) and 4 controls. Scores on live ICARS assessment had ranged from 0 to 7 for controls and 11 to 74 for ataxic subjects (clinically very mildly affected to wheelchair-bound). Inter-rater correlation was very high for the total score (Kendall's omega 0.994, 95% confidence interval, 0.988-0.997), and high to very high for each component subscore (0.791 for speech to 0.994 for posture/gait). All correlations were significant at P < 0.00001. The ICARS exhibits very high inter-rater reliability even without prior observer standardisation and is sensitive to a range of ataxia severities from very mild to severe.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activities of Daily Living / classification
  • Adult
  • Disability Evaluation
  • Female
  • Friedreich Ataxia / classification
  • Friedreich Ataxia / diagnosis*
  • Humans
  • Male
  • Middle Aged
  • Neurologic Examination / statistics & numerical data*
  • Observer Variation
  • Spinocerebellar Ataxias / classification
  • Spinocerebellar Ataxias / diagnosis*
  • Wheelchairs