Perceived benefits and barriers of increased dietary fiber consumption in subjects with type 2 diabetes: validation of a questionnaire

Background: This study was conducted to develop and validate a scale in order to assess perceived benefits and barriers (decisional balance) for improving dietary fiber consumption in patients with type 2 diabetes (T2D). Methods: In order to develop the scale, focus-group discussions, in-depth interviews and literature review were carried out. Validity of the questionnaire was assessed using content validity, face validity and construct validity. The factor structure of the questionnaire was also extracted by performing both principle component analysis (PCA) and confirmatory factor analyses. Reliability was then estimated using internal consistency and test-retest analysis. Two groups of T2D patients participated in the study. 146 T2D patients participated in the content validity and the other 265 T2D patients were those whose data were used for the confirmatory factor analysis. Results: The mean age of the participants was 52.3±7.6 years. PCA indicated two components representing benefits (Cronbach’s α=0.75) and barriers (Cronbach’s α=0.71). Confirmatory factor analysis supported the two-component structure [Goodness of Fit Index = 0.94, χ 2/df=1.56 (χ ² =118.28, df=76, p 0.001), RMSEA=0.046]. The Test–retest results, measured by interclass correlation (ICC), for all the items were between 0.62 and 0.78. Conclusion: The designed questionnaire is valid and reliable to assess perceived benefits and barriers of dietary fiber intake in patients with T2D.