Development and validation of the short Crohn's disease work disability questionnaire

Abstract

Background: The aim was to develop and validate a self-reported short Crohn's disease work disability questionnaire (sCDWDQ). Methods: (1) Development of a shortened questionnaire - Patients' responses to the validation process (n 108) of a previously developed, 16-item Spanish Crohn's disease work disability questionnaire (CDWDQ) were analyzed using the Rasch model for multiple response items. After this process, a 9-item sCDWDQ was obtained. (2) Validation phase - The validation assessed the questionnaire's convergent validity, discriminant validity, test-retest reproducibility, and internal consistency. Spearman rank correlation, t test, intra-class correlation and Cronbach's alpha were used for the analysis. Results: One hundred fifty-one patients were included in the validation phase. (1) Convergent validity was confirmed by correlations between the sCDWDQ and clinical activity (r 0.66, P < 0.01), the short inflammatory bowel disease questionnaire IBDQ-9 (r 0.74, P < 0.001), Euroqol-5D (r 0.63, P < 0.01), the EuroQol-5D visual analog scale (r 0.54, P < 0.01), and overall work impairment (r 0.66, P < 0.01); (2) Discriminant validity - sCDWDQ scores were higher in patients with active disease (20.1 ± 6.3 versus 13.0 ± 3.8 inactive, P < 0.001), in those requiring previous sick leave (19.6 ± 6.9 versus no sick leave 14.2 ± 4.8, P < 0.01) and in those requiring hospitalization (20.0 ± 7.3 [n 29] versus no hospitalization 14.1 ± 7.3 [n 90], P < 0.01); (3) Internal consistency was also good (Cronbach's alpha 0.92); and (4) Reproducibility - sCDWDQ measures obtained 2 weeks apart showed an excellent intraclass correlation coefficient of 0.92 (95% confidence interval, 0.90-0.94). Conclusions: The self-reported sCDWDQ appears to be a simple, valid, and reliable tool for measuring work disability in Crohn's disease.