title: E-Cigarette Susceptibility as a Predictor of Youth Initiation of E-Cigarettes.
abstract: BACKGROUND
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Psychiatry, CMHC, Yale School of Medicine, New Haven, CT.
authors.forename: Krysten W
authors.initials: KW
authors.lastname: Bold
authors.affiliation: Department of Psychiatry, CMHC, Yale School of Medicine, New Haven, CT.
authors.forename: Grace
authors.initials: G
authors.lastname: Kong
authors.affiliation: Department of Psychiatry, CMHC, Yale School of Medicine, New Haven, CT.
authors.forename: Dana A
authors.initials: DA
authors.lastname: Cavallo
authors.affiliation: Department of Emergency Medicine, Yale School of Medicine, New Haven, CT.
authors.forename: Deepa R
authors.initials: DR
authors.lastname: Camenga
authors.affiliation: Department of Psychiatry, CMHC, Yale School of Medicine, New Haven, CT.
authors.forename: Suchitra
authors.initials: S
authors.lastname: Krishnan-Sarin
mesh_terms: D000293:Adolescent; D004198:Disease Susceptibility; D066300:Electronic Nicotine Delivery Systems / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006306:Health Surveys; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D012574:Schools; D012907:Smoking / Q000453:epidemiology / Q000523:psychology*; D013334:Students / Q000523:psychology* / Q000706:statistics & numerical data; D062789:Tobacco Products / Q000706:statistics & numerical data*