Association between electronic nicotine delivery systems and electronic non-nicotine delivery systems with initiation of tobacco use in individuals aged < 20 years. A systematic review and meta-analysis

Background: This systematic review described the association between electronic nicotine delivery systems and electronic non-nicotine delivery systems (ENDS/ENNDS) use among non-smoking children and adolescents aged <20 years with subsequent tobacco use. Methods: We searched five electronic databases and the grey literature up to end of September 2020. Prospective longitudinal studies that described the association between ENDS/ENNDS use, and subsequent tobacco use in those aged < 20 years who were non-smokers at baseline were included. The Joanna Briggs Institute Critical Appraisal Checklist was used to assess risk of bias. Data were extracted by two reviewers and pooled using a random-effects meta-analysis. We generated unadjusted and adjusted risk ratios (ARRs) describing associations between ENDS/ENNDS and tobacco use. Findings: A total of 36 publications met the eligibility criteria, of which 25 were included in the systematic review (23 in the meta-analysis) after exclusion of overlapping studies. Sixteen studies had high to moderate risk of bias. Ever users of ENDS/ENNDS had over three times the risk of ever cigarette use (ARR 3⋅01 (95% CI: 2⋅37, 3⋅82; p<0⋅001, I²: 82⋅3%), and current cigarette use had over two times the risk (ARR 2⋅56 (95% CI: 1⋅61, 4⋅07; p<0⋅001, I²: 77⋅3%) at follow up. Among current ENDS/ENNDS users, there was a significant association with ever (ARR 2⋅63 (95% CI: 1⋅94, 3⋅57; p<0⋅001, I²: 21⋅2%)), but not current cigarette use (ARR 1⋅88 (95% CI: 0⋅34, 10⋅30; p = 0⋅47, I²: 0%)) at follow up. For other tobacco use, ARR ranged between 1⋅55 (95% CI 1⋅07, 2⋅23) and 8⋅32 (95% CI: 1⋅20, 57⋅04) for waterpipe and pipes, respectively. Additionally, two studies examined the use of ENNDS (non-nicotine devices) and found a pooled adjusted RR of 2⋅56 (95% CI: 0⋅47, 13⋅94, p = 0.035). Conclusion: There is an urgent need for policies that regulate the availability, accessibility, and marketing of ENDS/ENNDS to children and adolescents. Governments should also consider adopting policies to prevent ENDS/ENNDS uptake and use in children and adolescents, up to and including a ban for this group.