Systematic review, meta-analysis with subgroup analysis of hypnotherapy for irritable bowel syndrome, effect of intervention characteristics.

Background: Hypnotherapy has been shown to be effective at relieving global gastrointestinal symptoms (GGS) in irritable bowel syndrome (IBS). This study examines the impact of hypnotherapy delivery and participant characteristics on IBS outcomes.

Methods: This systematic review searched CINAHL, Cochrane Library, Conference Citation Index, Embase, PubMed, PsycARTICLES, PsychINFO, Science Citation index-expanded, Social Science Citation Index. Titles and abstracts, then full-text articles were screened against inclusion criteria: trials with a concurrent comparator of hypnotherapy in adults with IBS diagnosed using Manning or ROME criteria, which provided symptom data. Included studies were extracted and assessed for bias using Cochrane Collaboration 2011 guidance. Random-effects meta-analysis was conducted with sub-group analysis to assess the impact of delivery characteristics on outcomes.

Results: Twelve trials were included, 7 in the meta-analyses. Hypnotherapy reduced the risk of GGS, but this was not statistically significant, (standardised mean difference (SMD) 0.24, [-0.06, 0.54], I 66 %). Higher frequency of sessions (≥1/week) reduced GGS (SMD 0.45 [0.23,0.67] I 0 %), as did higher volumes of intervention (≥8 sessions with ≥6 h of contact) (SMD 0.51 [0.27,0.76] I 0 %) and group interventions (SMD 0.45 [0.03, 0.88] I 62 %). Only volume of intervention produced a significant effect between the subgroups.

Conclusion: This review suggests that high volume hypnotherapy is more beneficial than low and should be adopted for GDH. Both high frequency and group interventions are effective in reducing GGS in IBS. However, the sample size is small and more studies are needed to confirm this.