Validity and reliability of the Japanese versions of cognitive and behavioral scales for irritable bowel syndrome

Background The Cognitive Scale for Functional Bowel Disorders (CS-FBD) and Irritable Bowel Syndrome-Behavioral Responses Questionnaire (IBS-BRQ) are a useful measures to assess cognitive-behavioral aspects in individuals with IBS. This study aimed to confirm the reliability and validity of the Japanese versions of the CS-FBD (CS-FBD-J) and IBS-BRQ (IBS-BRQ-J). Methods Participants comprised 192 students and 22 outpatients diagnosed with irritable bowel syndrome (IBS). There were 76 students who met the diagnostic criteria for IBS and two students who received treatment for IBS. Participants completed questionnaires containing the CS-FBD-J, IBS Severity Index (IBS-SI), Visceral Sensitivity Index (VSI), 24-item Dysfunctional Attitudes Scale (DAS-24), Hospital Anxiety and Depression Scale (HADS), and Social Adaptation Self-evaluation Scale (SASS). Results Our exploratory factor analysis revealed that the CS-FBD-J had a unidimensional factor structure and that the factor loadings for two of the 25 items were less than 0.4. The IBS-BRQ-J had a two-factor structure, and the factor loadings for eight of the 26 items were less than 0.4. The confirmatory factor analysis for the 18-item version of IBS-BRQ-J showed that the model fit indices were not sufficient. The CS-FBD-J and IBS-BRQ-J had significant, moderate correlations with the IBS-SI and VSI in the IBS and control groups. Correlation between the DAS-24 and the CS-FBD-J was not significant. The CS-FBD-J and IBS-BRQ-J were significantly correlated to the HADS and SASS (IBS-BRQ-J) only in the IBS group. The scores of CS-FBD-J and IBS-BRQ-J showed significant group differences between the IBS patient group, non-patient IBS group, and control group. The internal consistencies of the CS-FBD-J and IBS-BRQ-J were high. The item-total correlation analysis for the CS-FBD-J and IBS-BRQ-J showed that the correlations between each item and the total score were significant. Conclusion This study confirmed the reliability and validity of the 23-item version of the CS-FBS-J and the 18-item version of the IBS-BRQ-J with the deletion of items with low factor loadings. Regarding the IBS-BRQ-J, two factor structures were confirmed (factor 1: behavior obsessed with abdominal symptoms, factor 2: avoidance of abdominal symptoms and associated difficulties) although the model fit of the structure needs further study.