VAPGAMO trial protocol: a cluster-randomised controlled evaluation of a digital game-based learning intervention to reduce adolescent vaping intention in Malaysian public secondary schools

ABSTRACT Introduction Youth vaping remains a global public health challenge. We will evaluate a pragmatic, theory-driven digital game-based learning intervention (VAPGAMO), delivered in public secondary schools to reduce adolescents’ intention to vape at 3-month follow-up. Methods and analysis Parallel cluster-randomised controlled trial with schools as clusters. Eight public secondary schools in an urban Southeast Asian district (Klang, Malaysia) will be randomised 1:1 to intervention or wait-list control. The intervention is a single 90-minute, facilitator-led module grounded in the Theory of Planned Behaviour. Surveys at baseline, immediately post-intervention, and 3 months. The primary outcome is intention to vape at 3 months. Secondary outcomes are knowledge, attitudes, injunctive norms, and refusal self-efficacy (perceived behavioural control). Pre-specified implementation outcomes include acceptability, fidelity, reach, time-on-task, and cost per student. Primary analysis will use generalised estimating equations with cluster-robust standard errors, adjusted for baseline covariates; intracluster correlation coefficient and design effect will be reported; intention-to-treat will be applied. Ethics and dissemination Ethical approval: Universiti Putra Malaysia JKEUPM-2024-887; approvals from the Ministry of Education, Malaysia. Findings will be disseminated in peer-reviewed outlets and shared with education and health authorities to inform school-health programming. De-identified data and code will be made available upon publication, subject to approvals. Trial registration This study was registered with the Thai Clinical Trial Registry (TCTR) [Ref No. TCTR20241222001], registered on December 22, 2024. Strengths and limitations of this study Pragmatic cluster-randomised design embedded in routine public schools, enhancing external validity for similar systems. Theory-driven digital module with pre-specified implementation outcomes to inform scale-up decisions. Analysis plan uses appropriate cluster methods with ICC reporting. Single 90-minute dose and 3-month follow-up may limit durability of effects. Conducted in one district; generalisability to other settings will be empirically assessed via implementation metrics.