Evaluation of a family-focused intervention to promote adolescent mental health and family relationships (phase 3 of MOST): protocol for a randomised controlled trial.

introductionParenting interventions have shown promise in improving mental well-being for parents and children and strengthening family relationships. Parenting for lifelong health (PLH) is an open-access, evidence-informed programme that aims to improve positive parenting practices, reduce family violence and promote mental health, particularly in low-resource settings. This study will evaluate the implementation and (cost-)effectiveness of an adapted version of the PLH for Parents and Teens programme. It will focus on supporting positive parenting, communication, mental health and well-being of adolescents and their caregivers in North Macedonia and Moldova. METHODS AND ANALYSIS: This multicountry hybrid type 1 effectiveness-implementation randomised waitlist-controlled trial will recruit 660 adolescents aged 10-14 years and their caregivers through schools, Youth Clinics and community partner organisations, including vulnerable and linguistically diverse families. The intervention group will receive the adapted PLH programme with assessments conducted postintervention and at 6-month follow-up. The waitlist control group will receive the adapted PLH programme after completion of the intervention group's 6-month post-baseline assessment. Primary outcomes include adolescent emotional problems, family functioning, parenting practices, adolescent and caregiver quality of life. Secondary outcomes assess a range of mental well-being, family and other psychosocial outcomes. Other prespecified outcomes include implementation and cost outcomes. Primary analyses will compare intervention and waitlist control groups at postintervention and 6-month follow-up using intention-to-treat, baseline-adjusted linear mixed models. A within-trial economic evaluation will include cost-utility analysis and cost-effectiveness analysis. A macroeconomic analysis will assess broader economic impacts using public financing and budget impact analysis. The study uses a mixed-methods process evaluation, and integrates qualitative data, budget impact analysis and simulation modelling to inform scale-up considerations. ETHICS AND DISSEMINATION: The study has received ethical approval from all relevant sites. Results will be disseminated through peer-reviewed publications, scientific conferences and webinars, newsletters, social media and open-access platforms, alongside engagement with researchers, clinicians, policymakers and the public. The Family-Focused Adolescent & Lifelong Health Promotion project uses a targeted communication and dissemination strategy for families, implementers and policy stakeholders to promote the adoption and scale-up of evidence-informed, open-access parenting interventions for adolescents and caregivers in low-resource settings. Dissemination focuses primarily on North Macedonia and Moldova while also engaging actors across the wider Eastern European region. TRIAL REGISTRATION NUMBER: NCT07240571.