Validation of the Italian translation of the Inflammatory bowel disease questionnaire

Background: Health-related quality of life is an important measure of treatment outcome; its evaluation requires the use of internationally validated ad hoc questionnaires. The McMaster Inflammatory Bowel Disease Questionnaire (IBDQ) is the most used specific instrument. Aim: To assess the validity and reliability of the Italian translation of the IBDQ. Methods: The IBDQ underwent forward and backward translation; 13 patients were enrolled for cognitive testing of the Italian version to increase clarity. For field testing, 113 patients (65 with Crohn's disease and 48 with ulcerative colitis) completed both the IBDQ and the generic instrument 36-item Short Form Health Survey scale (SF-36). Results: Data quality was optimal with high completeness and low floor and ceiling effect. Item internal consistency was satisfied for 100% of patients, while discriminant validity showed a few items with higher correlations with other scales. Cronbach's alpha coefficient was 0.96. Test-retest correlations indicated good reliability (Pearson R 0.81). Exploratory factor analysis indicated that the original grouping of the item was suboptimal. The score proved sensitive to disease activity, gender and quality of life as measured by the SF-36. Conclusions: The Italian translation of the McMaster Inflammatory Bowel Disease Questionnaire sounds natural and is easy to understand. A field test gave results comparable to other international validations, supporting its use in cross-national surveys.