Prevalence of Adolescent Cannabis Vaping: A Systematic Review and Meta-analysis of US and Canadian Studies.

Importance: Vaping products were initially designed to deliver nicotine as a tobacco cigarette substitute (eg, electronic cigarettes) but are now frequently used to deliver psychoactive substances, such as cannabis and its derivatives. Large, nationally representative surveys, such as Monitoring the Future, found that approximately 1 in 3 grade-12 students vaped cannabis in 2018 alone.

Objective: To summarize the findings of epidemiological studies that reported the global prevalence of cannabis vaping in adolescents by survey year and school grades.

Data Sources: PubMed, PsycINFO, Scopus, and Web of Science were searched systematically on August 19, 2020, for studies published globally between January 1, 2003, and August 19, 2020.

Study Selection: Publications that reported the prevalence of cannabis vaping in adolescents in the general population were included.

Data Extraction And Synthesis: Study characteristics and prevalence estimates were extracted from each article. Random-effects meta-analysis based on the DerSimonian and Laird method and meta-regression were performed on lifetime, 12-month, and 30-day prevalence estimates. Meta-regression was also conducted using survey year and school grades as moderators.

Main Outcomes And Measures: Prevalence of cannabis vaping.

Results: Seventeen studies met the eligibility criteria (n = 198 845 adolescents). Although no restrictions were imposed on study location, all 17 studies were from the US and Canada. Across all school grades, the pooled prevalence increased for lifetime use (6.1% in 2013-2016 to 13.6% in 2019-2020), use in the past 12 months (7.2% in 2017-2018 to 13.2% in 2019-2020), and use in the past 30 days (1.6% in 2013-2016 to 8.4% in 2019-2020). Heterogeneity across studies was large. The limited evidence from studies using similar survey and study designs suggested that adolescents' preference for cannabis products other than dried herbs, which usually contain higher Δ9-tetrahydrocannabinol levels, may have shifted over time.

Conclusions And Relevance: The findings of this study suggest that the prevalence of cannabis vaping has increased among adolescents in the US and Canada and that more effective preventive and response measures are required.

Trial Registration: PROSPERO Identifier: CRD42020219644.