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Systematic Review
"To systematically review evidence to answer the following questions: what theories of change inform PYD interventions addressing substance use and violence? What characteristics of participants and contexts are identified as barriers to and facilitators of implementation and receipt in process evaluations of PYD? What is the effectiveness and cost-effectiveness of PYD in reducing substance use and violence? What characteristics of participants and contexts appear to moderate, or are necessary and sufficient for, PYD effectiveness?"
"32,394 unique references were identified and 48 were included. A total of 16 reports described theories, 13 (10 studies) evaluated processes and 25 (10 studies) evaluated outcomes."
"How PYD might promote health is currently undertheorised. Implementation can be challenging. We found little evidence that current PYD interventions delivered outside school reduce substance use or violence. However, these may not constitute a test of the effectiveness of the PYD model, as some included interventions that, although meeting our inclusion criteria, were not exemplars of PYD."