E-Cigarette Susceptibility as a Predictor of Youth Initiation of E-Cigarettes.

Introduction: Identifying youth at risk for future e-cigarette use is critical for informing prevention efforts. Prior research established measures of susceptibility to conventional cigarettes, and this study aimed to examine whether items adapted for e-cigarette susceptibility predicted subsequent e-cigarette use among never e-cigarette users.

Methods: Longitudinal school-wide survey data were collected from middle and high school students in Fall 2013 (wave 1) and Spring 2014 (wave 2). Among never e-cigarette users at wave 1 (n = 1720), e-cigarette susceptibility was measured by two items assessing anticipation of experimenting with e-cigarettes in the future and willingness to use an e-cigarette if offered by a best friend. Logistic regression models examined susceptibility as a predictor of e-cigarette initiation and past 30-day use 6 months later at wave 2. Models were clustered by school and controlled for sex, age, race, SES, and other substance use (alcohol, marijuana, and other tobacco).

Results: In total, 8.9% (n = 153) of youth initiated e-cigarettes and 3.7% (n = 63) reported past 30-day use at wave 2. E-cigarette susceptibility was a significant independent predictor of subsequent initiation (OR = 4.27, 95% CI = 3.12-5.85) and past 30-day e-cigarette use (OR = 5.10, 95%CI = 3.38-7.68) 6 months later. Susceptible youth were more likely to be male, older, and have used alcohol, marijuana, or other tobacco products.

Conclusions: These findings provide initial support for adapting two susceptibility items to identify adolescents at risk for future e-cigarette use. Identifying strategies that are effective for targeting susceptible youth and preventing future e-cigarette use will be critical areas for future research.

Implications: More than a quarter of the sample who reported both a willingness to try e-cigarettes if offered by a best friend and anticipation of experimenting with e-cigarettes in the future went on to try e-cigarettes within the academic year, suggesting that targeting this group will be critical for preventing youth e-cigarette initiation. There were notable demographic differences between susceptible and non-susceptible youth, suggesting targeting e-cigarette prevention efforts to male students who have used other substances may be especially important for preventing future e-cigarette use. Research is needed to determine the most effective prevention strategies to reach susceptible youth.