A comprehensive questionnaire for the assessment of health-related quality of life in coeliac disease (CDQL)

Abstract: Coeliac disease (CD) is a chronic immune-mediated disease in genetically susceptible individuals, induced by ingested gluten. The treatment for CD is a lifelong gluten-free diet (GFD). The GFD involves restrictions in diet that may impact on a person’s Health-Related Quality of Life (HRQoL). Aim: The aim of the present study was to develop the Coeliac Disease Quality of Life questionnaire (CDQL): a comprehensive CD-specific HRQoL measure that can be completed by children, adolescents, and adults or by proxy. Methods: The questionnaire was developed in three phases. In phase 1, focus group methods and qualitative analysis of verbatim transcripts generated CD-specific items for a prototype instrument to sensitively captured patient concerns. In phase 2, CD patients completed the prototype CDQL. The questionnaire was refined through analysis of data and cognitive interviewing. In phase 3, the final version of the CDQL was answered by Danish respondents. The psychometric properties of the CDQL were assessed, and the HRQoL data were analyzed. Results: The CDQL was completed by 422 respondents. The CDQL has 12 patient background items, 2 generic HRQoL items, and 30 CD-specific HRQoL item. The CD-specific HRQoL items were distributed on eight scales with acceptable to excellent reliability. Comprehensiveness and understandability was shown by feedback from cognitive interviewing from children, adolescents, and adults. Content validity was ensured by involving patients and clinicians in the development of the questionnaire. Sensitivity of the questionnaire was demonstrated in differences found between children, adolescents, and adult’s perception of their HRQoL in relation to having CD. Conclusions: The CDQL comprehensively measures HRQoL in CD, and is psychometrically robust. The questionnaire may prove useful in tracking HRQoL in CD across age groups.