Development and validation of a knowledge, attitudes and practices questionnaire in the dietary management of irritable bowel syndrome

Objective To develop and validate a questionnaire assessing knowledge, attitudes and practices in the dietary management of IBS. Subjects/Methods An initial pool of 151 questions was generated addressing three domains (knowledge, attitudes, practices). Academic/senior clinical dietitians ( n = 5) provided written feedback and a focus group ( n = 4 gastroenterology dietitians) was undertaken to evaluate content and face validity of the question-items. Items considered irrelevant were removed and the refined questionnaire was administered to dietitians with different levels of IBS experience ( n = 154) for further psychometric testing. Item reduction analysis was assessed by item difficulty index, discrimination index and point-biserial correlation. Construct validity was assessed via principal component analysis (PCA) and the ‘known-groups’ method. Internal reliability was assessed by Kuder–Richarson Formula 20 and Cronbach’s alpha coefficient and external reliability by interclass correlation coefficient among participants who completed the instrument at baseline and two weeks later ( n = 28). Results Face and content validity resulted in the removal of 61 items from the initial 151 items. Psychometric testing was applied to the refined 90-item questionnaire administered to participating dietitians, resulting in the final 46-item questionnaire. Six factors were extracted by PCA with varimax rotation explaining 59.2% of the total variance. Partial confirmatory factor analysis showed an acceptable model fit (χ2/df = 2.11, CFI = 0.97, TLI = 0.96, RMSEA = 0.08, SRMR = 0.05). Significant differences were found in sum scores among dietitians with different levels of IBS experience. Internal reliability was >0.7 for each factor. External reliability was >0.6 for each factor and >0.7 for overall items of each domain. Conclusion A validated questionnaire to use in practice and research to assess knowledge, attitudes and practices in the dietary management of IBS has been developed.