A Simple Validated Gluten-Free Diet Adherence Survey for Adults With Celiac Disease

Background & Aims: Celiac disease is an increasingly prevalent disorder. To monitor response to treatment in clinical and research settings, it is essential to accurately measure gluten-free diet (GFD) adherence in a standardized manner. The aim of this study was to develop a valid and reliable Celiac Dietary Adherence Test (CDAT). Methods: Items and domains believed to be essential for successful GFD adherence were used to develop an 85-item survey with input from patient focus groups. The survey was administered to 200 individuals with biopsy-proven celiac disease who underwent standardized dietician evaluation (SDE) and serologic testing. Results: Of the initial 85 items, 41 were correlated highly with the SDE (P < .01). Responses for all 200 participants for the 41 items were entered into a single database. Computer-generated randomization produced a derivation cohort of 120 subjects and a validation cohort of 80. By using the derivation cohort, a 7-item questionnaire was developed using logistic regression. The additive score based on these items was correlated highly with the SDE in both the derivation and validation cohorts (P < .001) and performed significantly better than immunoglobulin A tissue transglutaminase titers in receiver operating characteristic curve analysis with areas under the curve of 0.830 and 0.652, respectively. Conclusions: The CDAT is a clinically relevant, easily administered, 7-item instrument that allows for standardized evaluation of GFD adherence and is superior to tissue transglutaminase serology. The CDAT may be useful in both research and clinical settings.