Validating a Brief Screening Questionnaire for IBS Patients With Symptoms Aggravated by GI-Specific Anxiety

Abstract

Introduction: IBS is a common GI disorder whose key mechanism is brain-gut dysregulation caused by the interplay of peripheral and central mechanisms. While central factors are recognized as having an important role in disrupting the neuroenteric axis, their impact on IBS symptoms is difficult for gastroenterologists (GEs) to gauge because assessment instruments (fMRI, psychological testing) are expensive and/or impractical to administer outside of research settings. In the wake of health care reform emphasizing increased accountability for patient care through measurable outcomes, there is an urgent need to develop quality indicators that clinicians can efficiently use in busy clinic settings. We sought to develop a brief, easy to administer version of the Visceral Sensitivity Index (VSI), a 15-item measure of GI-specific anxiety (GSA) that has been found to mediate the relationship between general distress and GI symptom severity and is a key predictor of IBS diagnosis. Methods: Subjects include 232 Rome III-diagnosed IBS patients (F, 78%; Mean age = 40) who were assessed at pretreatment baseline of an NIH trial. Subjects completed testing including the VSI, IBS Quality of Life (IBSQOL), Brief Symptom Inventory (mental distress), 11-point abdominal pain scale, IBS Symptom Severity Scale (IBS-SSS), SOMS-7 (somatization), and SF-12 Fatigue. Results: An exploratory factor analysis yielded 2 factors consisting of 4 items each accounting for 31% of the variance. Both factors showed good internal consistency (Cronbach’s alpha >0.70) and were strongly correlated with the full measure (r ≥0.87). Factor 1 tapped a tendency to ruminate about the adverse consequences of IBS symptoms (worry), while Factor 2 tapped a tendency for mild visceral sensations (e.g., abdominal discomfort) to activate more extreme negative thoughts (Cognitive Reactivity or CR). The predictive validity of these 2 subscales was compared to the total VSI score in a set of regression analyses predicting IBS outcomes while controlling for confounding variables. The relationship between both factors and outcomes were in the predicted directions. Cognitive reactivity predicted abdominal pain, IBSQOL, somatization, and distress above and beyond the predictive power of worry. Worry was a stronger predictor of previous treatment relief, fatigue, and IBS-SSS than CR. In all cases, use of either shorter VSI versions explained a similar amount of variance in outcome measures as the longer measure. Conclusion: Data lend strong psychometric support to 2 4-item VSI measures, both of which may be useful in indexing level of central arousal that disrupts brain-gut interactions, informing clinical decision making, and monitoring outcome of complex IBS patients seen in busy clinical settings.