A Systematic Review and Meta-analysis of School-Based Preventive Interventions Targeting E-Cigarette Use Among Adolescents.

This study aimed to examine the efficacy of school-based e-cigarette preventive interventions via a systematic review and meta-analysis. We searched Medline, Embase, PsycINFO, Scopus, CINAHL, Cochrane, and clinical trial registries for studies published between January 2000 and June 2023 using keywords for e-cigarettes, adolescents, and school. Of 1566 double-screened records, 11 met the criteria of targeting adolescents, evaluating an e-cigarette preventive intervention, being conducted in a secondary school, using a randomized controlled trial (RCT), cluster RCT, or quasi-experimental design, and comparing an intervention to a control. Pre-specified data pertaining to the study design, outcomes, and quality were extracted by one reviewer and confirmed by a second, and where necessary, a third reviewer. Meta-analyses found no evidence that school-based interventions prevented e-cigarette use at the longest follow-up, which ranged between 6 and 36 months post-intervention (OR = 0.43, 95% CI = 0.16, 1.12; p = 0.09). However, subgroup analyses identified significant effects at post-test and when studies with < 12-month follow-up were omitted. No effect was found for tobacco use at the longest follow-up (OR = 1.01, 95% CI = 0.65, 1.59, p = 0.95); however, reductions in past 30-day tobacco use (OR = 0.59, 95% CI = 0.39, 0.89, p = 0.01) which encompassed e-cigarettes in some studies were identified. Narrative synthesis supported these mixed results and found some school-based interventions prevented or reduced e-cigarette and/or tobacco use; however, some increased use. School-based interventions were also associated with improved knowledge (SMD =  - 0.38, 95% CI =  - 0.68, - 0.08, p = 0.01), intentions (SMD =  - 0.15, 95% CI =  - 0.22, - 0.07, p = 0.0001), and attitudes (SMD =  - 0.14, 95% CI =  - 0.22, - 0.06; p = 0.0007) in the short term. Overall, the quality of evidence was low-to-moderate. School-based interventions hold the potential for addressing e-cigarette use, however, can have null or iatrogenic effects. More high-quality research is needed to develop efficacious interventions, and schools must be supported to adopt evidence-based programs. This is the first systematic review and meta-analysis to examine the efficacy of school-based preventive interventions for e-cigarette use. It provides crucial new knowledge about the efficacy of such interventions in preventing e-cigarette use and improving other outcomes (e.g., tobacco use, knowledge, intentions, attitudes, and mental health) among adolescents and the key characteristics associated with efficacious interventions. Our findings have important practical implications, highlighting future research directions for the development and evaluation of e-cigarette preventive interventions, along with the need to provide support to schools to help them identify and adopt evidence-based programs.