BACKGROUND: Celiac disease (CeD) is a systemic, immune-mediated disorder characterized by inflammation in the small intestine. It is triggered by the ingestion of gluten and is associated with substantial patient burden. This study aimed to revise the Celiac Disease Symptom Diary (CDSD), a novel patient-reported outcome measure developed for use with patients with CeD, to reflect regulatory guidance and evaluate the content validity of the measure in both adults and adolescents.
METHODS: In-depth qualitative interviews were conducted with 32 patients with CeD (16 adults [≥18 years] and 16 adolescents [>12 years to <18 years]) to document their symptoms and to cognitively debrief and refine the CDSD.
RESULTS: Interview outcomes revealed a similar symptom experience among adolescents and adults. The top five most frequently reported symptoms were abdominal pain (90.6%), tiredness (68.8%), bloating (62.5%), nausea (62.5%) and diarrhea (56.3%). Participants found the CDSD easy to understand and complete, and reported no difficulty recalling symptoms over the past 24 hours. Cognitive debriefing of participants identified several refinements to the CDSD. Uncertainty regarding the terms “abdominal pain” and “bowel movement”, was expressed by some adolescent participants and additional terms were included to ease understanding.
After refinement, the final measure (CDSD v2.1) consisted of the five symptom severity items listed above, which during qualitative interviews were consistently reported as relevant and important by participants. The measure remained easy to understand and complete, and adequately evaluated symptoms. Based on interviewer observations and participant feedback, frequency of bowel movements, diarrhea and vomiting were included in a separate module that could be administered alongside the CDSD v2.1.
CONCLUSIONS:Following refinements, the CDSD v2.1 adequately and appropriately assessed symptoms of CeD and was well understood and easily completed. These observations support the content validity of the measure across adults and adolescents. The CDSD v2.1 will undergo psychometric validation in upcoming studies.
