Original article—alimentary tract
A Simple Validated Gluten-Free Diet Adherence Survey for Adults With Celiac Disease

https://doi.org/10.1016/j.cgh.2008.12.032Get rights and content

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.

Section snippets

Methods

An expert panel consisting of gastroenterologists, dieticians, psychologists, and individuals with CD was assembled to discuss the factors important in living with CD and influential in GFD adherence. Over a series of meetings, a set of 5 domains relevant to GFD adherence were elucidated ad hoc, including the following: (1) CD-related symptoms, (2) disease-specific knowledge, (3) self-efficacy, (4) reasons for keeping a GFD, and (5) perceived adherence to the GFD. From these domains, a bank of

Results

The demographic characteristics of the initial study population and the validation cohort were not significantly different than that of the overall CD population seen at Beth Israel Deaconess Medical Center (BIDMC) with the exception of classic symptoms at onset, which were reported less frequently in the overall BIDMC group than the study cohort (P = .04) (Table 1, Table 2). Overall, the population studied was highly adherent to the GFD with 74.6% having excellent or good GFD adherence as

Discussion

In recent years, CD has gone from being understood as a relatively infrequent disorder with a nearly optimal treatment to a very common disorder with frequent lack of GFD adherence and for which there is a great need for new therapies and rigorous evaluation of disease outcomes.18 Progress in both areas has been limited by the lack of validated disease-specific instruments. Although it is arguable that clinical symptoms of CD may be evaluated using a generic symptom index such as the

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    Conflicts of interest The authors disclose no conflicts.

    Funding This study was supported by charitable donations from patients to the Celiac Center at Beth Israel Deaconess Medical Center (BIDMC), the Celiac Sprue Association, NIH T32 training grant DK07760, and the Harvard-Thorndike General Clinical Research Center M01 RR01032.

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