title: Acceptance and commitment therapy - Do we know enough? Cumulative and sequential meta-analyses of randomized controlled trials.
abstract: Acceptance and Commitment Therapy (ACT) has accrued a substantial evidence base. Recent systematic and meta-analytic reviews suggest that ACT is effective compared to control conditions. However, these reviews appraise the efficacy of ACT across a broad range of presenting problems, rather than addressing specific common mental health difficulties. Focussing on depression and anxiety we performed a meta-analysis of trials of ACT. We incorporated sequential meta-analysis (SMA) techniques to critically appraise the sufficiency of the existing evidence base. Findings suggest that ACT demonstrates at least moderate group and pre-post effects for symptom reductions for both anxiety and depression. However using SMA findings are more qualified. There is currently insufficient evidence to confidently conclude that ACT for anxiety is efficacious when compared to active control conditions or as primary treatment for anxiety. Similarly, using SMA, there is currently insufficient evidence to suggest a moderate efficacy of ACT for depression compared to active control conditions. To stimulate further research we offer specific estimates of additional numbers of participants required to reach sufficiency to help inform future studies. We also discuss the appropriate strategies for future research into ACT for anxiety given the current evidence suggests no differential efficacy of ACT in the treatment of anxiety compared to active control conditions.
authors.affiliation: Universitätsmedizin Rostock, Germany. Electronic address: Thomas.hacker@med.uni-rostock.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hacker
authors.affiliation: NHS Fife, Scotland, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Stone
authors.affiliation: University of Edinburgh, Scotland, United Kingdom.
authors.forename: Angus
authors.initials: A
authors.lastname: MacBeth
mesh_terms: D064869:Acceptance and Commitment Therapy; D001007:Anxiety / Q000628:therapy*; D003863:Depression / Q000628:therapy*; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D018401:Sample Size
keywords: Acceptance and commitment therapy; Anxiety; Depression; Mental health; Sequential meta-analysis; Treatment efficacy