Behavioral avoidance moderates the effect of exposure therapy for irritable bowel syndrome: A secondary analysis of results from a randomized component trial.

Past research has failed to identify consistent moderators of outcomes in psychological treatments for irritable bowel syndrome (IBS). The aim of this study was to test previously identified mediators as potential moderators of the effects of exposure therapy on IBS symptoms in a previously published randomized component trial. In total, 309 participants with IBS were randomized to internet-delivered cognitive behavioral treatment that included exposure (ICBT) or to the same treatment protocol without exposure (ICBT-WE) and were asked to report on gastrointestinal symptoms at pretreatment, posttreatment and weekly during the treatment. Pretreatment scores of The Visceral Sensitivity Index (VSI) and The Irritable Bowel Syndrome Behavioral Responses Questionnaire (IBS-BRQ) (i.e., gastrointestinal anxiety and avoidance behavior) were evaluated as predictors and moderators. Piecewise latent growth curve models were employed to evaluate moderators during distinct phases of the trial, prior to and following the onset of exposure in ICBT. Results revealed that pretreatment scores on IBS-BRQ (avoidance) moderated the effect of exposure therapy during the specific phase in which exposure was implemented in ICBT, with higher avoidance scores linked to stronger positive effects of exposure. VSI did not serve as predictor nor moderator. Adding exposure to CBT seems to be especially important for persons with moderate to high levels of avoidance behaviors in order to reduce gastrointestinal symptoms.