Prospective validation study of the International Classification of Functioning, Disability and Health score in Crohn's disease and ulcerative colitis.

BACKGROUND AND AIMS Inflammatory bowel diseases (IBD) may result in disability. We aim to validate a novel scoring system for the IBD disability index (IBD-DI), and identify predictors of disability and its correlation with work absenteeism. METHODS This prospective IBD ambulatory clinic cohort study measured IBD-DI, Crohn's Disease Activity Index (CDAI) for Crohn's disease (CD) or partial Mayo score (pMayo) for ulcerative colitis (UC), IBDQ quality-of-life, and Work Productivity and Activity Impairment. Negative IBD-DI represented greater disability. Validation tests were performed and predictors and extent of work absenteeism were determined. RESULTS 166 consecutive subjects were recruited (75 CD, 41 UC, 50 controls). IBD-DI correlated with CDAI (r=-0.77, P<0.001), pMayo (r=-0.82, P<0.001) and IBDQ (r=0.86, P<0.001). IBD-DI differentiated CD, and UC from controls (medians -7, -4, +10; P<0.001) with a score of >3.5 identifying controls with 94% sensitivity and 83% specificity (area-under-curve 0.92). Stable patients had unchanged IBD-DI (P=ns) but not in those who relapsed (P<0.001). Intraclass correlation was 0.89 and Cronbach's alpha of internal consistency was 0.94. Diagnosis age, sex, phenotype, perianal disease, prior surgery, steroid-use and disease duration did not influence the IBD-DI but active use of biological agents significantly reduced disability (P=0.03). 21.6% of IBD patients had moderate-severe disability equating to missing >25% of work hours in the previous week. Multivariate analysis identified that only IBD-DI to be predictive of unemployment status (OR: 0.94; 95% CI: 0.89-0.99). CONCLUSIONS The IBD-DI is a valid tool measuring disability in both CD and UC and correlates with workforce participation. It is a potential useful tool in the assessment of participation restriction and activity limitation. TRIAL REGISTRATION ACTRN12613000903785.