School-Family Linked and Online-Offline Combined Tobacco Control Intervention for Adolescents: Protocol for a Cluster Randomized Pilot Trial.

Abstract

Background: Tobacco use remains a leading preventable cause of disease, yet adolescent-focused tobacco prevention is underexploited. We developed a real-time adaptive intervention that combines school-family collaboration with online-offline delivery (via WeChat mini-programs, games, and curricula) to address adolescents' overlooked role as health catalysts and persistent household secondhand smoke (SHS) exposure.

Objective: This study aims to evaluate the feasibility and effectiveness of this school-family linked and online-offline combined tobacco control intervention in improving adolescents' tobacco-related knowledge, attitudes, and behaviors, reducing student smoking prevalence and household SHS exposure, and assessing implementation process indicators (fidelity, participation, and satisfaction) to inform future scale-up.

Methods: This is a cluster randomized pilot trial guided by the PRISM (Practical, Robust Implementation and Sustainability Model) framework. We recruited approximately 1280 seventh-grade students (aged 12-13 years) from 9 secondary schools across 3 districts of Beijing (urban, peri-urban, and suburban). Classes were the unit of randomization, allocated 1:1:1:1 to a control group (standard education) and 3 intervention arms (online only, offline only, and combined online-offline). The 7-component intervention (lectures, pamphlets, microvideos, peer games, knowledge competitions, online quizzes, and a digital mini-game) was delivered through a school-family digital platform. The coprimary outcomes are changes in tobacco-related knowledge and attitudes, along with implementation process indicators (fidelity, participation, and satisfaction) and feasibility; and the secondary outcomes are tobacco-related behaviors (smoking prevalence and quit attempts) and household SHS exposure. A mixed methods evaluation based on PRISM assessed recipient, provider, and health system levels.

Results: Baseline data collection was completed in November 2024. Data analysis began in late 2025, with final results expected in 2026. The findings will determine whether the intervention improves adolescents' tobacco knowledge and attitudes, reduces smoking and household SHS exposure, and provides insights into implementation fidelity and satisfaction across delivery modes.

Conclusions: This pilot trial will establish the feasibility and preliminary effectiveness of the intervention. If successful, it may mobilize school-family partnerships using widely available digital platforms to support sustained tobacco control among adolescents and reduce household SHS exposure.