title: Identifying effective techniques within psychological treatments for irritable bowel syndrome: a meta-analysis.
abstract: OBJECTIVE
  Psychological interventions can alleviate the symptoms of irritable bowel syndrome (IBS) and psychological distress commonly reported among IBS sufferers. However, the theoretical underpinnings and intervention techniques used by such interventions vary considerably. This study aimed to identify which theoretical approaches and techniques lead to greater improvements in IBS symptoms and psychological well-being within psychological interventions for IBS.
  
  
  METHODS
  Outcome data were extracted from 48 randomized controlled trials testing psychological treatments for IBS. Theoretical intervention targets and intervention techniques of each study were identified. Cumulative effect sizes were calculated for pain, bowel dysfunction, composite symptom scores, psychological distress, and health-related quality of life. Comparative analyses contrasted the effect sizes of studies which included each intervention technique to those which did not.
  
  
  RESULTS
  Cumulatively, interventions significantly improved all outcomes, with effect sizes (Hedges' g) ranging from 0.32 to 0.64. Interventions which stated a theoretical intervention target, prompted self-monitoring of symptoms and cognitions, provided tailored feedback linking symptoms and cognitions, utilized problem solving or assertiveness training and provided general support had greater effects upon symptom and well-being outcomes than interventions which did not (all P<.05). Across all studies, improvements in psychological distress were associated with improvements in composite symptom scores (P<.01).
  
  
  CONCLUSIONS
  This study identifies a set of techniques associated with improvements in IBS symptoms and psychological well-being in existing interventions, and provides initial evidence for the link between improvements in psychological distress and IBS composite symptom scores. These findings can aid the development and refinement of psychological treatments for IBS.
authors.affiliation: University of Oxford, UK. Electronic address: Julia.Henrich@seh.ox.ac.uk.
authors.forename: Julia F
authors.initials: JF
authors.lastname: Henrich
authors.affiliation: University of Helsinki, Finland; Newcastle University, UK.
authors.forename: Keegan
authors.initials: K
authors.lastname: Knittle
authors.affiliation: Leiden University, The Netherlands.
authors.forename: Véronique
authors.initials: V
authors.lastname: De Gucht
authors.affiliation: Nictiz - The National IT Institute for Healthcare, The Netherlands.
authors.forename: Simone
authors.initials: S
authors.lastname: Warren
authors.affiliation: University of Stirling, UK.
authors.forename: Stephan U
authors.initials: SU
authors.lastname: Dombrowski
authors.affiliation: Leiden University, The Netherlands.
authors.forename: Stan
authors.initials: S
authors.lastname: Maes
mesh_terms: D000328:Adult; D003071:Cognition; D015928:Cognitive Behavioral Therapy; D006304:Health Status; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000523:psychology* / Q000628:therapy*; D011788:Quality of Life; D016896:Treatment Outcome
keywords: Intervention techniques; Irritable bowel syndrome; Meta-analysis; Psychological distress; Psychological interventions