Effectiveness of School-Based Interventions to Prevent Tobacco Initiation and Improve Smoking-Related Knowledge in Children Aged 6–12 Years: A Systematic Review and Meta-Analysis of Randomized Trials

Tobacco initiation often occurs early in life, yet evidence on school-based prevention for children remains fragmented. This systematic review and meta-analysis examined randomized controlled trials of school-based smoking prevention interventions initiated among children aged 6–12 years, evaluating smoking initiation and knowledge. PubMed/MEDLINE, PsycINFO, and Scopus were searched without date restrictions. The review followed PRISMA2020 and was registered (PROSPERO: CRD420251090900). Risk of bias was assessed using RoB2, and results were pooled with heterogeneity quantified using I². Thirty-two studies were included, predominantly involving children aged 10–12 years from different countries. Most studies reporting sex distribution included approximately 45–55% female participants. Seven studies contributed to the meta-analysis of smoking initiation. The pooled estimate indicated lower odds of smoking initiation among intervention participants (OR = 0.82, 95%CI = 0.70–0.94; p = 0.007; I²=30.96%). Knowledge outcomes were not meta-analysed due to heterogeneity, although interactive and skills-based programmes showed more consistent improvements than information-focused approaches. Overall, the findings suggest that school-based programmes initiated during childhood may modestly reduce smoking initiation, supporting the relevance of preventive efforts before smoking behaviours become established in adolescence.