The Causative Classification of Stroke system An international reliability and optimization study

Research output: Contribution to journalArticle


Background: Valid and reliable ischemic stroke subtype determination is crucial for well-powered multicenter studies. The Causative Classification of Stroke System (CCS, available at is a computerized, evidence-based algorithm that provides both causative and phenotypic stroke subtypes in a rule-based manner. We determined whether CCS demonstrates high interrater reliability in order to be useful for international multicenter studies. Methods: Twenty members of the International Stroke Genetics Consortium from 13 centers in 8 countries, who were not involved in the design and development of the CCS, independently assessed the same 50 consecutive patients with acute ischemic stroke through reviews of abstracted case summaries. Agreement among ratings was measured by kappa statistic. Results: The kappa value for causative classification was 0.80 (95% confidence interval [ CI] 0.78-0.81) for the 5-subtype, 0.79 (95% CI 0.77-0.80) for the 8-subtype, and 0.70 (95% CI 0.69-0.71) for the 16-subtype CCS. Correction of a software-related factor that generated ambiguity improved agreement: kappa = 0.81 (95% CI 0.79-0.82) for the 5-subtype, 0.79 (95% CI 0.77-0.80) for the 8-subtype, and 0.79 (95% CI 0.78-0.80) for the 16-subtype CCS. The kappa value for phenotypic classification was 0.79 (95% CI 0.77-0.82) for supra-aortic large artery atherosclerosis, 0.95 (95% CI 0.93-0.98) for cardioembolism, 0.88 (95% CI 0.85-0.91) for small artery occlusion, and 0.79 (0.76-0.82) for other uncommon causes. Conclusions: CCS allows classification of stroke subtypes by multiple investigators with high reliability, supporting its potential for improving stroke classification in multicenter studies and ensuring accurate means of communication among different researchers, institutions, and eras. Neurology (R) 2010;75:1277-1284


  • E. M. Arsava
  • E. Ballabio
  • T. Benner
  • J. W. Cole
  • M. P. Delgado-Martinez
  • M. Dichgans
  • F. Fazekas
  • K. L. Furie
  • K. Illoh
  • K. Jood
  • S. Kittner
  • J. J. Majersik
  • M. J. Macleod
  • W. J. Meurer
  • J. Montaner
  • A. A. Olugbodi
  • A. Pasdar
  • P. Redfors
  • R. Schmidt
  • P. Sharma
  • A. B. Singhal
  • A. G. Sorensen
  • C. Sudlow
  • V. Thijs
  • B. B. Worrall
  • J. Rosand
  • H. Ay
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Neurology
Original languageEnglish
Pages (from-to)1277-1284
Issue number14
Publication statusPublished - 2010
Publication categoryResearch