title: The quantitative validation of non-endoscopic disease activity indices in ulcerative colitis.
abstract: BACKGROUND
  Ulcerative colitis disease activity indices have not been formally validated.
  
  
  OBJECTIVE
  To analise quantitatively the psychometric and performance validity of two non-endoscopic indices for ulcerative colitis, the Simple Clinical Colitis Activity Index and the Seo Index.
  
  
  METHODS
  In 66 patients with ulcerative colitis, the measurement of disease activity was repeated with the two non-endoscopic indices, St Mark's Index, and the Inflammatory Bowel Disease Questionnaire. Psychometric validity was evaluated by measuring the content, construct, criterion-convergent and criterion-predictive validity on a 0-1 scale. Performance validity was evaluated by measuring the reproducibility and responsiveness on a 0-1 scale.
  
  
  RESULTS
  The Simple Clinical Colitis Activity Index had good to excellent psychometric and performance validity, while the Seo Index had moderate to excellent psychometric validity and moderate to good performance validity. The Simple Clinical Colitis Activity Index had weaknesses in content validity and in responsiveness. The Seo Index had weaknesses in content validity, construct validity and responsiveness.
  
  
  CONCLUSIONS
  These two non-endoscopic indices for ulcerative colitis have good psychometric and performance validity, and are now the most rigorously validated disease activity indices for ulcerative colitis. The Simple Clinical Colitis Activity Index appears to have better overall validity. Quantitative evaluation identifies weaknesses in disease activity indices, and can lead to better disease activity indices for ulcerative colitis.
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA. phiggins@umich.edu
authors.forename: P D R
authors.initials: PD
authors.lastname: Higgins
authors.forename: J
authors.initials: J
authors.lastname: Leung
authors.forename: M
authors.initials: M
authors.lastname: Schwartz
authors.forename: J
authors.initials: J
authors.lastname: Mapili
authors.forename: P A
authors.initials: PA
authors.lastname: Wren
authors.forename: E M
authors.initials: EM
authors.lastname: Zimmermann
mesh_terms: D003093:Colitis, Ulcerative / Q000175:diagnosis*; D003113:Colonoscopy; D006305:Health Status Indicators; D006801:Humans; D008137:Longitudinal Studies; D011594:Psychometrics / Q000706:statistics & numerical data*; D012720:Severity of Illness Index