Supplementary Material for: Efficacy of Acceptance and Commitment Therapy for Suicide and Self-harm: A Systematic Review and Meta-analysis

Introduction: Self-injurious thoughts and behaviors (SITBs) are major public health issues worldwide. In recent years, there has been a growing body of research investigating the application of acceptance and commitment therapy (ACT) for SITBs. This study systematically reviews and meta-analyzes the effectiveness of ACT in reducing SITBs.
Methods: We systematically searched six databases and examined the reference lists of relevant studies. Studies that explored the effectiveness of ACT versus control conditions for reducing SITBs were included. Effect sizes were calculated using Hedges’ g with the random effect model. Subgroup analyses and meta-regression were also performed.
Results: A total of 48 studies (N = 4,719) were included in this review. The results indicated that ACT outperformed control conditions in alleviating suicide ideation (g = -0.64), suicide attempt (g = -0.66), self-harm (g = -1.53), non-suicidal self-injury (g = -0.59), and overall SITBs (g = -0.99) at post-treatment. Also, ACT was effective in reducing suicide ideation (g = -2.15), non-suicidal self-injury (g = -1.18), and overall SITBs (g = -1.52) at follow-up. Moderator analyses revealed that ACT was more successful in mitigating suicide ideation when delivered in a group format or in Eastern countries. Similarly, studies conducted in Eastern countries, or those employing direct interventions, reported greater efficacy in addressing overall SITBs.
Conclusion: This review highlights the effectiveness of ACT in reducing SITBs and suggests that it may serve as a promising alternative strategy to standard treatment for SITBs. More high-quality and large-scale randomized controlled trials are required to substantiate our findings.