Objectives: Measures of cognitive-affective processes believed to underlie Irritable Bowel Syndrome (IBS) symptom expression are used widely in both clinical and research settings. When combined, these measures can be time-consuming and it is not clear whether they evaluate distinct or overlapping constructs. With this study, we seek to identify the most critical cognitive-affective components contributing toward the expression of IBS and to identify which items in these constructs might be streamlined into a single, brief self-report measure.
Patients and methods: This measure was developed according to Food and Drug Administration guidelines for patient-reported outcome development. First, authors consolidated existing cognitive-affective measures (visceral sensitivity, anxiety sensitivity, and pain catastrophization) into a single questionnaire. Second, a principal components factor analysis was carried out on the basis of responses from a sample of participants with IBS. Third, on the basis of the results of the factor analysis, items were reduced to the final brief self-report measure and preliminary validity/reliability analyses (Cronbach's α, correlation with other related constructs) were carried out.
Results: An initial, 44-item measure was created. In all, 179 patients with ROME-III IBS completed an online survey. Principal component analysis and item reduction yielded a 15-item scale with three factors: pain catastrophization, visceral hypervigilance, and extraintestinal hypervigilance. The final three factors showed comparable internal consistencies (α>0.90), concurrent validity, and predictive validity compared with the original 44 items.
Conclusion: Although more research is warranted, the 15 items identified appear to provide an accurate measure of two important cognitive-affective constructs in the IBS population.