1. Among adolescents aged 12-17 years, e-cigarette use was linked with new onset marijuana use one year later, as determined by a large longitudinal survey.
2. Younger adolescents aged 12-14 years had a higher association between e-cigarette use and future marijuana use as compared with older adolescents aged 15-17 years.
Evidence Rating Level: 2 (Good)
Study Rundown: Previous studies have evaluated the link between traditional cigarette use and marijuana. However, despite e-cigarettes becoming more popular among youth, there remains a paucity of literature establishing a link between e-cigarettes and future marijuana use among teens. In this study, a large cohort was surveyed over 2 years with 10 364 participants ultimately reaching final analysis. E-cigarette use, when correcting for other covariates, was found to be independently linked with recent new onset marijuana use in teens. The relationship was stronger for younger teens aged 12-14 as compared to older teens aged 15-17. In addition, e-cigarette use had a positively linked dose-dependent relationship with future heavy marijuana use. The link was more strongly associated with female African Americans with poorer grades. As the data was survey driven, it was subject to recall bias and other confounders not incorporated into the analysis. Nonetheless, the study adds to the body of literature needed to reinforce policy change and advocacy with regards to a relatively new form of substance use that is attractive to youth. Not only does this study lend to future advocacy efforts, but the data may be used in the clinical setting to promote a healthy lifestyle for teens.
Study Author, Hongying Dai, M.D., talks to 2 Minute Medicine: Health Services & Outcomes Research, Children’s Mercy Hospital, University of Missouri-Kansas City:
E-cigarette use predicts subsequent marijuana use among youth, with a stronger association among young adolescents. Our findings suggest that the widespread use of e-cigarettes among youth may have implications for uptake of other drugs of abuse beyond nicotine and tobacco products. Our findings highlight the importance of policy and education to reduce risks for youth. It is important for parents, health providers and educators to advise youth about the risks of e-cigarette use. Policies to prevent youth use of e-cigarettes and reduce youth access to e-cigarettes, such as expanding smoke-free policies and Tobacco 21 policies, should be considered as well.
In-Depth (retrospective cohort): A retrospective analysis was performed using national data from the Population Assessment of Tobacco and Health (PATH) survey from 2013-2015. Teens who reported never smoking marijuana were separated into 2 groups, those that had smoked e-cigarettes in the past and those that had not. The groups were followed longitudinally a year later to assess for rates of new onset marijuana use. Multivariable logistic regression was used to establish the dose related associations. After adjusting for covariates, e-cigarette use had significantly increased odds (aOR 1.9, 95% Cl:1.4-2.5) for marijuana use in the following year. Breaking the data down by age, younger teens (ages 12-14) exposed to e-cigarette use had increased odds (aOR 2.7, 95% Cl:1.7-4.3), whereas older teens (ages 15-17) had a slightly lower odds (aOR 1.6, 95% Cl;1.2-2.3) of marijuana use in the next year. In addition, there was a significant (P <.05) dose-dependent association between e-cigarette use and heavy marijuana use in younger teens, but not in older teens.
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