title: The Inflammatory Bowel Disease-Disability Index: validation of the Portuguese version according to the COSMIN checklist.
abstract: OBJECTIVE
  Recently, the Inflammatory Bowel Disease-Disability Index (IBD-DI) was developed to assess disability in inflammatory bowel disease (IBD). Our aim was to validate the Portuguese version of IBD-DI according to the COnsensus-based Standards for the selection of the health Measurement INstruments (COSMIN) recommendations.
  
  
  METHODS
  After translation into Portuguese, the IBD-DI was administered by two interviewers to IBD patients at baseline and after 4 weeks and 4 months. We evaluated reliability (internal consistency, test-retest, and inter-rater reliability and measurement error), construct validity, responsiveness, and interpretability.
  
  
  RESULTS
  At baseline, 129 patients (73=Crohn's disease; 56=ulcerative colitis) completed the IBD-DI. After 4 weeks and 4 months, 118 and 89 patients repeated the questionnaire, respectively. Factor analysis confirmed the unidimensionality of the scale and reduced the final version to 14 items. The Cronbach's α was 0.88. The intraclass correlation coefficients were 0.87 and 0.99 for test-retest (baseline and 4 weeks) and inter-rater reliability, respectively. The smallest detectable change was 18.64 at the individual level and 1.87 at the group level. IBD-DI scores correlated negatively with the total, physical, and mental scores of Short Form-36 items. The change score of IBD-DI between baseline and 4 months correlated negatively with the clinical evolution of patients. The minimal important change was 16.96. IBD-DI scores ranged from 0 to 78.6, with a mean of 21.8±18.1. Female sex, professional inactivity, and clinical disease activity were associated with higher IBD-DI scores.
  
  
  CONCLUSIONS
  The Portuguese version of IBD-DI obtained is a reliable, valid, responsive, and interpretable (at the group level) tool to assess disability in Portuguese IBD patients.
authors.affiliation: aDepartment of Gastroenterology, Hospital de Braga bSchool of Health Sciences, University of Minho, Braga, Portugal.
authors.forename: João B
authors.initials: JB
authors.lastname: Soares
authors.forename: Rafaela
authors.initials: R
authors.lastname: Pereira
authors.forename: Juliana M
authors.initials: JM
authors.lastname: Costa
authors.forename: Bruno
authors.initials: B
authors.lastname: Arroja
authors.forename: Raquel
authors.initials: R
authors.lastname: Gonçalves
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D057189:Checklist; D003093:Colitis, Ulcerative / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D003424:Crohn Disease / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D004185:Disability Evaluation; D004651:Employment; D005260:Female; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D015588:Observer Variation; D011174:Portugal; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D055815:Young Adult