Background The mental health and wellbeing of care-experienced children and young people (i.e. foster care, kinship care, residential care) is poorer than non-care-experienced populations. The Care-experienced cHildren and young people’s Interventions to improve Mental health and wEll-being outcomes Systematic review (CHIMES) aimed to synthesise the international evidence base for interventions targeting subjective wellbeing, mental health and suicide amongst care-experienced young people aged ≤ 25 years. Methods For the first phase of the review, we constructed an evidence map identifying key clusters and gaps in interventions and evaluations. Studies were identified through 16 electronic databases and 22 health and social care websites, in addition to expert recommendations, citation tracking and screening of relevant systematic reviews. We charted interventions and evaluations with a summary narrative, tables and infographics. Results In total, 64 interventions with 124 associated study reports were eligible. The majority of study reports were from the USA (n = 77). Interventions primarily targeted children and young people’s skills and competencies (n = 9 interventions), the parental functioning and practices of carers (n = 26), or a combination of the two (n = 15). While theoretically under-specified, interventions were largely informed by theories of Attachment, Positive Youth Development, and Social Learning Theory. Current evaluations prioritised outcomes (n = 86) and processes (n = 50), with a paucity of study reports including theoretical descriptions (n = 24) or economic evaluations (n = 1). Interventions most frequently targeted outcomes related to mental, behavioural or neurodevelopmental disorders, notably total social, emotional and behavioural problems (n = 48 interventions) and externalising problem behaviours (n = 26). There were a limited number of interventions targeting subjective wellbeing or suicide-related outcomes. Conclusions Future intervention development might focus on structural-level intervention theories and components, and target outcomes related to subjective wellbeing and suicide. In accordance with current methodological guidance for intervention development and evaluation, research needs to integrate theoretical, outcome, process and economic evaluation in order to strengthen the evidence base. Systematic review registration PROSPERO CRD42020177478.

IntroductionThe mental health and well-being of children and young people who have been in care (ie, care-experienced) are a priority. There are a range of interventions aimed at addressing these outcomes, but the international evidence-base remains ambiguous. There is a paucity of methodologically robust systematic reviews of intervention effectiveness, with few considering the contextual conditions under which evaluations were conducted. This is important in understanding the potential transferability of the evidence-base across contexts. The present systematic review will adopt a complex systems perspective to synthesise evidence reporting evaluations of mental health and well-being interventions for care-experienced children and young people. It will address impact, equity, cost-effectiveness, context, implementation and acceptability. Stakeholder consultation will prioritise a programme theory, and associated intervention, that may progress to further development and evaluation in the UK.Methods and analysisWe will search 16 bibliographic databases from 1990 to June 2020. Supplementary searching will include citation tracking, author recommendation, and identification of evidence clusters relevant to included evaluations. The eligible population is children and young people (aged ≤25 years) with experience of being in care. Outcomes are (1) mental, behavioural or neurodevelopmental disorders; (2) subjective well-being; (3) self-harm; suicidal ideation; suicide. Study quality will be appraised with methodologically appropriate tools. We will construct a taxonomy of programme theories and intervention types. Thematic synthesis will be used for qualitative data reporting context, implementation and acceptability. If appropriate, meta-analysis will be conducted with outcome and economic data. Convergent synthesis will be used to integrate syntheses of qualitative and quantitative data.Ethics and disseminationWe have a comprehensive strategy for engagement with care-experienced children and young people, carers and social care professionals. Dissemination will include academic and non-academic publications and conference presentations. Ethical approval from Cardiff University’s School of Social Sciences REC will be obtained if necessary.PROSPERO registration numberCRD42020177478.

Background: The mental health and wellbeing of care-experienced children and young people (i.e. foster care, kinship care, residential care) is poorer than non-care-experienced populations. The Care-experienced cHildren and young people’s Interventions to improve Mental health and wEll-being outcomes Sytematic review (CHIMES) systematic review aimed to synthesise the international evidence-base for interventions targeting subjective wellbeing, mental health and suicide amongst care-experienced young people aged ≤ 25 years. Methods: For the first stage of the review we constructed an evidence map identifying key clusters and gaps in interventions and evaluations. Studies were identified through 16 electronic databases and 22 websites, in addition to expert recommendations, citation tracking and screening of relevant systematic reviews. We charted interventions and evaluations with a summary narrative, tables and infographics. Results: In total, 64 interventions with 124 associated study reports were eligible. The majority of study reports were from the USA (n=77). Interventions primarily target children and young people’s skills and competencies (n=9 interventions), the parental functioning and practices of carers (n=26), or a combination of the two (n=15). While theoretically under-specified, interventions are largely informed by theories of Attachment, Positive Youth Development, and Social Learning Theory. Current evaluations prioritise outcome (n=86) and process (n=50), with a paucity of study reports including theoretical descriptions (n=24) or economic evaluations (n=1). Interventions most frequently target outcomes related to mental health, neurodevelopment and behavioural outcomes, notably total social, emotional and behavioural problems (n=48 interventions) and externalizing problem behaviours (n=26). There are a limited number of interventions targeting subjective wellbeing or suicide-related outcomes. Conclusions: Future intervention development might focus on structural-level intervention theories and components, and target outcomes related to subjective wellbeing and suicide. In accordance with current methodological guidance for intervention development and evaluation, research needs to integrate theoretical, outcome, process and economic evaluation in order to strengthen the evidence-base. PROSPERO Registration: CRD42020177478