Systematic Review and Individual Participant Data Meta-Analysis: Reducing Self-Harm in Adolescents: Pooled Treatment Effects, Study, Treatment and Participant Moderators.

Objective
Self-harm is common in adolescents and a major public health concern. Evidence for effective interventions that stop repetition is lacking. This individual-participant-data (IPD) meta-analysis of randomised controlled trials (RCTs) aimed to provide robust estimates of therapeutic intervention effects and explore which treatments are best suited to different subgroups.
Method
We searched databases and trial registers, to January-2022. RCTs compared therapeutic intervention to control, targeted adolescents aged 11-18 with a history of self-harm and receiving clinical care and reported on outcomes related to self-harm or suicide attempt. Primary outcome was repetition of self-harm at 12 months post-randomization . Two-stage random-effects IPD meta-analyses were conducted overall and by intervention. Secondary analyses incorporated aggregate data (AD) from RCTs without IPD. PROSPERO registration: CRD42019152119.
Results
We identified 39 eligible studies; 26 provided IPD (3,448 participants), 7 provided AD (698 participants). There was no evidence that intervention/s were more or less effective than controls at preventing repeat self-harm by 12 months in IPD (odds ratio (OR)=1.06 [95% CI 0.86, 1.31], studies=20, n=2,949) or IPD+AD (OR=1.02 [95% CI 0.82, 1.27], studies=22, n=3,117) meta-analyses and no evidence of heterogeneity of treatment effects on study and treatment factors. Across all interventions, participants with multiple prior self-harm episodes showed evidence of improved treatment effect on self-harm repetition 6-12 months after randomization (OR=0.33 [95% CI 0.12, 0.94], studies=9, n=1,771).
Conclusion
This large-scale meta-analysis of RCTs provided no evidence that therapeutic intervention was more, or less, effective than control for reducing repeat self-harm. We observed evidence indicating more effective interventions within youth with two or more self-harm incidents. Funders and researchers need to agree on a core set of outcome measures to include in subsequent studies.