Transcultural adaptation and validation of the CDAT questionnaire (Celiac Dietary Adherence Test) for adult patients

Abstract

In Iran, there is no valid available questionnaire for assessing adherence level to Gluten-free diet (GFD). So, in the present study, we aimed to translate the celiac disease adherence test (CDAT) questionnaire in Persian and evaluate its validity and reliability. Materials and Methods: In the present cross-sectional study, CDAT was translated and back-translated by three bilingual professional translators. Content validity was evaluated by 12 gastroenterologists and nutritionists. To assess the construct validity, 230 patients with celiac disease (CD) were randomly selected from the national celiac disease registry database. Internal consistency of the items and test-retest reliability were assessed by Cronbach’s alpha and Intraclass Correlation Coefficient (ICC). To assess the convergent validity of the questionnaire, correlation coefficient between CDAT score and immunoglobulin A tissue transglutaminase (Anti-tTG-IgA) titer was assessed. Results: The CVI, CVR, and impact score of the Persian version of CDAT (Pv-CDAT) were 0.97, 0.95, and 4.61 respectively. Three significant factors were extracted and according to the confirmatory factor analysis the three-factor model had adequate fitness (chi-square p-value of 0.74, RMSEA: 0.001 [95% CI: 0.001-0.083], CFI: 1, SRMR: 0.04, and coefficient of determination: 0.78). The questionnaire had good feasibility with the floor effect of 3.1% and the ceiling effect of 0.4%. Moreover, it has high internal consistency (Cronbach-alpha: 0.71) and test-retest reliability (ICC: 0.78). The correlations between CDAT categories and anti-tTG-IgA categories showed a significant correlation between the two tests (r=0.53; P<0.001).