title: Electronic Cigarette Use by Youth: Prevalence, Correlates, and Use Trajectories From Middle to High School.
abstract: OBJECTIVE
  The aim of this study was to examine the use of electronic cigarettes (e-cigarettes) among adolescents over time, including correlates of lifetime use by eighth grade and trajectories of current use across ninth grade.
  
  
  METHODS
  Participants (N = 1,091) from seven school districts in Oregon, United States, completed four self-report surveys on substance use, from the spring of eighth grade (M age = 14.4 years old; standard deviation = .50) through the spring of ninth grade.
  
  
  RESULTS
  Overall, 27.7% of eighth graders had used e-cigarettes, and 16.8% were current e-cigarette users (used in the past 30 days); use did not significantly differ by gender or ethnicity. Correlates of e-cigarette lifetime use by eighth grade included lifetime and current use of marijuana, alcohol, cigarettes, and chewing tobacco. Five percent of students were "accelerators," on average using e-cigarettes 14 of the last 30 days in eighth grade, increasing to daily use (30/30 days) by the end of ninth grade. Across all substances, those in the accelerator group were more likely to have reported lifetime substance use by eighth grade and current substance use in ninth grade, compared to the "infrequent/no use" group.
  
  
  CONCLUSIONS
  A sizeable proportion of young adolescents are using e-cigarettes, and e-cigarette use is highly correlated with use of other substances, including marijuana. Adolescents who progress to daily e-cigarette use in high school are more likely to use other substances compared to low or nonusers. E-cigarettes may be a relatively new addition to a constellation of substances being actively used by a segment of the youth population.
authors.affiliation: Oregon Research Institute, Eugene, Oregon. Electronic address: erikaw@ori.org.
authors.forename: Erika
authors.initials: E
authors.lastname: Westling
authors.affiliation: Oregon Research Institute, Eugene, Oregon.
authors.forename: Julie C
authors.initials: JC
authors.lastname: Rusby
authors.affiliation: Oregon Research Institute, Eugene, Oregon.
authors.forename: Ryann
authors.initials: R
authors.lastname: Crowley
authors.affiliation: Oregon Research Institute, Eugene, Oregon.
authors.forename: John M
authors.initials: JM
authors.lastname: Light
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D066300:Electronic Nicotine Delivery Systems / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D009922:Oregon; D015995:Prevalence; D012574:Schools; D013334:Students / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires
keywords: Adolescents; E-cigarettes; Substance use