A meta-analytic approach of mechanisms of change in CBT interventions for Irritable Bowel Syndrome

Abstract

Background: Empirical data has shown that cognitive behavioral therapy (CBT) has small to medium effects in alleviating emotional distress and psychosomatic symptoms in Irritable Bowel Syndrome (IBS). However, the mechanism through which CBT employs its effects is less studied. Mediation analysis examines the extent to which an intermediate variable explains the effect of an intervention on different outcomes. Having said that, the current meta-analysis aims at identifying and assessing the impact of CBT mediators on IBS, identified in previous research. Methods: An extensive search of studies investigating the effects of CBT for IBS published before January 2017 was conducted. Studies selected had to clearly define CBT intervention, include IBS patients, report sufficient data to allow calculation of effect sizes and provide a clear mediation analysis of one or several variables on the outcome. Results: Several mediators that influence the effects of CBT on IBS symptomatology or quality of life were identified (e.g. illness perception, visceral sensitivity, catastrophizing, gastrointestinal symptom-specific anxiety). The statistical analysis also revealed CBT interventions have a greater effect on alleviating IBS symptoms severity rather than on reducing psychological distress. Limitation: Study differences between intervention, control groups, methodology and quantitative data presented in the articles, allowed us to conduct the meta-analytic analysis only on 6 studies from the initial 10 included. Discussion: Identifying mediators can have a significant role in improving our understanding of the psychosomatic mechanisms involved in IBS as well as the mechanisms of change we need to target when designing and implementing psychological interventions.