The Tobacco Road Begins With Electronic Cigarettes

William T. Basco, Jr., MD, MS


October 23, 2015

Association of Electronic Cigarette Use With Initiation of Combustible Tobacco Product Smoking in Early Adolescence

Leventhal AM, Strong DR, Kirkpatrick MG, et al
JAMA. 2015;314:700-707


Study Summary

The rapid increase in the popularity of electronic cigarettes (e-cigs) among adolescents has prompted ongoing concern that these products may serve as a gateway substance leading to consumption of combustible tobacco products. This study enrolled adolescents at 10 public high schools in Los Angeles and followed them longitudinally to assess whether e-cig use predicted who would go on to use combustible tobacco.

The baseline assessment for this study was conducted in the fall of 2013, when the students were in 9th grade. The students were again assessed in spring of 2014 and in the fall of 2014, when the students were in 10th grade. Surveys collected at each point included questions about whether the students had used e-cigs ("ever" at initial assessment or "in the past 6 months" at follow up), cigarettes, cigars, or other ways to inhale combustible tobacco smoke. The investigators used each student's response to the question about ever using e-cigs for the baseline classification of the adolescents into groups. The researchers also collected sociodemographic data (age, race, parental education, etc.) and environmental factors (smoking among household contacts, family history of smoking, and exposure to peer smoking). They measured mental health and behavioral variables (such as impulsivity) that correlated, in previous studies, with the likelihood of smoking. They measured baseline susceptibility to smoking by asking whether the students would likely try a cigarette if a friend offered one to them.

The sample included more than 2500 students whose data were available for analyses. Of those, 222 (8.8%) had ever used e-cigs at the first assessment. The mean age of the students was 14 years; 19% were Asian, 44% were Hispanic, 16% were white, and approximately 5% were black. In bivariate analyses, at baseline, having peers who smoked, impulsive tendencies, delinquent behavior, and positive measures of smoking susceptibility were all associated with having tried e-cigs, even among students who had never smoked combustible tobacco. At both the 6-month and 12-month follow-up assessments, students who had ever used e-cigs were more likely to have begun smoking tobacco products. For example, at the 12-month follow-up, 9.3% of the students who had not used e-cigs at baseline had tried combustible tobacco products compared with 25.2% of the students who had used e-cigs at baseline. Even after adjusting for all variables, use of e-cigs at baseline was associated with increased odds of using any combustible tobacco at follow-up (odds ratio [OR], 2.73; 95% confidence interval [CI], 2.00-3.73). Additional variables that increased the odds of smoking combustible products included lower parental education, the presence of peers who smoked tobacco at the baseline assessment, impulsivity, and delinquent behavior. The investigators concluded that baseline use of e-cigs in students was associated with initiation of combustible tobacco products within 12 months.


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