title: Emergence of electronic cigarette use in US adolescents and the link to traditional cigarette use.
abstract: Electronic cigarettes (e-cigarettes) are increasingly used by US adolescents and may be a gateway to traditional cigarette use. We examine rates of both products by age and examine differences in age-varying rates by sex and race/ethnicity.
  
  
  
  Data are from the 2014 National Youth Tobacco Survey, a national sample of US middle and high school students (n=22.007); students ages 11-19 were included. Past 30-day e-cigarette and traditional cigarette use were examined as a function of age; sex and race/ethnicity were included as moderators. The age-varying association between e-cigarette and traditional cigarette use was also examined.
  
  
  
  Rates of e-cigarette use increase faster than traditional cigarette use from ages 13-16. Compared to females, males had higher rates of e-cigarette use from ages 14-17.5 and traditional cigarette use from ages 15-18. Between ages 12-14, more Hispanic adolescents used e-cigarettes compared to White or Black adolescents; after age 14 Hispanics and Whites reported similar rates, peaking at twice the rate for Blacks. Hispanic adolescents report greater traditional cigarette use versus Whites between ages 12-13, but lower rates between ages 15-18. E-cigarette use was strongly associated with traditional cigarette use, particularly during early adolescence [OR>40 before age 12].
  
  
  
  Young Hispanic adolescents are at elevated risk for use of e-cigarettes and traditional cigarettes during early adolescence. During early adolescence, youth using e-cigarettes are more likely to smoke traditional cigarettes compared to youth not using e-cigarettes. The study of age-varying effects holds promise for advancing understanding of disparities in health risk behaviors.
authors.affiliation: The Methodology Center, The Pennsylvania State University, University Park, PA, USA; Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA, USA. Electronic address: SLanza@psu.edu.
authors.forename: Stephanie T
authors.initials: ST
authors.lastname: Lanza
authors.affiliation: The Methodology Center, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Russell
authors.affiliation: The Methodology Center, The Pennsylvania State University, University Park, PA, USA; Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Braymiller
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000328:Adult; D000367:Age Factors; D002648:Child; D000073865:Cigarette Smoking / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D066300:Electronic Nicotine Delivery Systems / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D011795:Surveys and Questionnaires; D014481:United States; D055815:Young Adult
keywords: Adolescence; Cigarettes; E-cigarettes; Time-varying effect modeling