CDDUX: A disease-specific health-related quality-of-life questionnaire for children with celiac disease

Objective: The development of a disease-specific, health-related, quality-of-life questionnaire for children ages 8 to 18 with celiac disease (CD), together with a parent-as-proxy version. Materials and Methods: We used a focus-group method (bottom-up approach) to investigate the impact of CD on children's everyday lives and selected 24 items to create a preliminary disease-specific questionnaire. This questionnaire, together with the complementary generic quality-of-life questionnaire DUX-25, was sent to 756 children with CD in the Netherlands and was returned by 530 of them. With the help of statistical analyses (Crorbach alpha, factor analysis, Pearson correlation, Student t test, paired samples t test, and item response theory), we tested the psychometric performance of the 24 items. Results: We reduced the questionnaire to 12 items: the Celiac Disease DUX (CDDUX). The CDDUX has 3 subscales: "Communication" (3), "Diet" (6), and "Having CD" (3). This questionnaire proved to be reliable, valid, and feasible and able to discriminate between perception of severity in cases of CD as assessed by parents. Conclusions: Children with a better perception of their own health status have a higher score on the CDDUX questionnaire. The whole group seems to have a lower quality of life than the healthy reference group on all domains of the DUX-25. The new disease-specific questionnaire CDDUX provides information about how children with CD think and feel about their illness. The questionnaire may enable researchers and clinicians to determine the consequences of this illness and the effects of clinical interventions on several aspects of daily living.