A Cluster- Randomized Controlled Trial Evaluating the MEST Work Strategy to Improve Health Literacy Among Upper Secondary School Students

This study is a cluster randomized controlled trial conducted in upper secondary schools, with schools serving as the unit of randomization to minimize contamination between students. A matched pair allocation design is used to ensure balance between trial arms. The anticipated enrollment is 12 schools (clusters).

Simulation based power analyses indicated that the primary analytic models yielded approximately 0.62-0.72 power to detect an effect size of d = 0.30 and were generally close to or exceeded 0.80 when the post test effect size was larger (d = 0.40).

The MEST work strategy is implemented during regular school hours by school health services and is designed to enhance students' ability to access, understand, evaluate, and apply health related information, with a specific focus on health literacy and mental well being. Data are collected using digitally administered questionnaires at baseline (T0), 4 months (T1), and 9 months (T2) following initiation of the intervention.

The primary outcome is general health literacy. Secondary outcomes include mental health literacy and mental well being. Prespecified secondary subgroup/moderator analyses will examine potential effect modification by gender, socioeconomic status, and minority, Indigenous, or immigrant background. Additional exploratory analyses will assess whether the dose of the MEST work strategy delivered is associated with outcomes. Outcome data are reported by students, while information on intervention dose is obtained from the school health services.