Study protocol of the e-Intervention Enhancing Mental Health in Adolescents (IMPROVA) project: a randomised controlled trial to promote adolescents’ mental health and well-being in four European countries

INTRODUCTION: This trial aims to evaluate the impact of the IMPROVA intervention programme in improving mental health, quality of life, and well-being in adolescents enrolled in secondary schools in four European countries. METHODS AND ANALYSIS: The IMPROVA intervention will be evaluated using a two-arm parallel group pragmatic cluster randomised controlled trial with an intervention and a wait-list control group. Secondary schools in France, Germany, Romania, and Spain were recruited. Originally, we estimated to enrol a total of 6000 students within 64 schools; that is, 16 schools per country. The IMPROVA programme is a multi-level intervention that provides tailored content for adolescents, families, and school staff. This content creates a unified and supportive framework that promotes mental health and social-emotional development among adolescents. A series of implementation strategies was planned to support the uptake of the programme into the education setting and among participants. Study outcomes were assessed at baseline, mid-term (during the intervention), postintervention (primary end point), and will be assessed at postintervention (secondary end-point; 6 months after postintervention). Overall mental health (Strengths and Difficulties Questionnaire) is the primary outcome. Secondary outcomes include: health-related quality of life, depression, anxiety, social isolation, and self-esteem. The trial will be evaluated regarding its effectiveness, cost-effectiveness, implementation, and social return on investment analysis. ETHICS AND DISSEMINATION: This study has received the approval of human research ethics committees in France (Comité de Protection des Personnes Ile-de-France VIII", No. 2024-A00201-46), Germany (Ulm University Ethics Committee, No. 186-24), Romania (The Research Ethics Subcommittee of the Babeș-Bolyai University of Cluj-Napoca, No. 14.146/23.09.2024), and Spain (CEIm Fundació Sant Joan de Déu, No. PIC-61-24). Results will be disseminated through peer-reviewed open-access publications and presentations at national and international conferences. Non-technical summaries will be shared with public health authorities, participants, and stakeholder organisations. All findings will be reported in aggregate form, ensuring no individual participant can be identified. TRIAL REGISTRATION NUMBER: NCT06556576.