Authors' objectives: Self-harm is common in adolescents and a major public health concern. Evidence for effective interventions is lacking. An individual participant data meta-analysis has potential to provide more reliable estimates of the effects of therapeutic interventions than conventional meta-analyses and to explore which treatments are best suited to certain groups.

Authors' results and conclusions: We identified 39 eligible studies, from 10 countries, where we sought individual participant data (18 studies with full sample eligibility, 21 with partial sample eligibility). We obtained individual participant data from 26 studies of 3448 eligible participants. We used published data from a further seven studies where individual participant data were not available for a combined individual participant data aggregate data meta-analysis (698 participants). For our primary outcome, repetition of self-harm, only six studies were rated as low risk of bias. There was no evidence that intervention/s were more or less effective than controls at preventing repeat self-harm by 12 months using individual participant data (odds ratios 1.06, 95% confidence interval 0.86 to 1.31) or individual participant data + aggregate data (odds ratios 1.02, 95% confidence interval 0.82 to 1.27) and no evidence of heterogeneity of treatment effects on study and treatment factors. We found no evidence that intervention was more or less effective than control for secondary outcomes, except general psychopathology and suicidal ideation at 12 and 6 months, respectively. Across all interventions, participants with multiple prior self-harm episodes showed evidence of improved treatment effect on self-harm repetition 6–12 months after randomisation [odds ratios 0.33 (95% confidence interval 0.12 to 0.94), studies = 9, n = 1771]. Modest evidence suggesting differential treatment effects based on participants’ age, gender, self-harm method, and anxiety levels are noted. More attention needs to be paid to seeking appropriate consent from study participants for data-sharing. We found no evidence that any therapeutic intervention (overall or by intervention) was more or less effective than control for reducing repeat self-harm. We are therefore unable to recommend any specific intervention to prevent repetition of self-harm in adolescents. We observed evidence and trends indicating more effective interventions within specific subgroups. Analysis was constrained due to scarcity of data concerning common baseline characteristics, outcomes, and follow-up lengths. We recommend efficient, adaptive platform trial designs to tackle research questions and ascertain the most effective interventions for different groups, covering available treatments.

Authors' methods: A systematic review and individual participant data meta-analysis of randomised controlled trials of therapeutic interventions to reduce repeat self-harm in adolescents with a history of self-harm and who had presented to clinical services. We searched Cochrane Library, EMBASE, trial registers and other databases for randomised controlled trials published in January 2022. Eligible randomised controlled trials compared any therapeutic intervention against a control, aimed to reduce self-harm in adolescents (11–18 years old), with past self-harm presenting to clinical services, and collected outcome data on self-harm or suicide attempts. Interventions reviewed were grouped into nine categories: cognitive–behavioural therapy; dialectical behaviour therapy; family therapy; group therapy; mentalisation based, psychodynamic, cognitive analytic therapy; multisystemic therapy; problem-solving, psychoeducation, support; postcards, tokens, documents (postcards/tokens); and other single session, brief interventions. Control interventions were all either treatment as usual or enhanced treatment as usual and were not usually well described. There were no ‘no treatment’ controls except in the postcard/document/token studies. Primary outcome was repetition of self-harm at 12 months. Other outcomes included repetition of self-harm at other time points, overall mental health, depressive symptoms, thoughts of suicide, quality of life and death. Two-stage random-effects individual participant data meta-analyses were conducted overall and by intervention, and to examine interaction between treatment received and participant characteristics. Secondary analyses incorporated aggregate data from randomised controlled trials without individual participant data. Metaregression explored moderating study effects. A significant limitation was missing individual participant data where authors were unable to share data; we offset this by including published data in secondary individual participant data plus aggregate meta-analysis. A wide range of interventions were evaluated and lacked replication. There was variability in the definitions and timings of outcomes, measures used for data collection, and available moderator data, with little consistency across studies.

Project Status: Completed

URL for project: https://www.journalslibrary.nihr.ac.uk/programmes/hta/NIHR135677

Year Published: 2026

URL for published report: https://www.journalslibrary.nihr.ac.uk/hta/published-articles/KKBB1164

URL for additional information: English

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: England, United Kingdom

DOI: 10.3310/KKBB1164

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk