title: E-Cigarettes and the Drug Use Patterns of Adolescents.
abstract: BACKGROUND
  This study examines the role of e-cigarettes in the drug use patterns of adolescents. Of specific interest is whether adolescent e-cigarette users fall into a group of (1) youth who do not use traditional drugs of abuse or (2) polysubstance users.
  
  
  METHODS
  Using latent class analysis, we identify major "classes" of substance users on the basis of recent use of e-cigarettes, alcohol, marijuana, cigarettes, and prescription drugs. Analyses are conducted separately for adolescents in 8th, 10th, and 12th grades. Data come from 16 615 participants in the 2014 Monitoring the Future survey.
  
  
  RESULTS
  Youth who do not use traditional drugs of abuse account for about 50% of e-cigarette users in 8th grade, 35% in 10th grade, and 17% in 12th grade. These youth come from a large "low-level users" group found in each grade, characterized by low probability of use for all substances (e-cigarette probability in this group for 8th graders = .046; 10th graders = .071; 12th graders = .027). Other e-cigarette users come from a smaller, "poly-users" group found in each grade, characterized by high-to-moderate probabilities (.83-.21) of using e-cigarettes and other substances. Specific to 12th grade is a third, additional polysubstance group characterized by high likelihood of e-cigarette use (.93).
  
  
  CONCLUSIONS
  The proportion of e-cigarette users who do not use traditional drugs of abuse is larger at younger ages. Longitudinal panel studies starting at 8th and 10th grades may best inform the current debate on whether e-cigarette use is a risk or protective factor for future transition to the use of other substances.
  
  
  CONCLUSIONS
  The proportion of e-cigarette users who do not use traditional drugs of abuse is larger at younger ages. Longitudinal panel studies starting at 8th and 10th grades may best inform the current debate on whether e-cigarette use is a risk or protective factor for future transition to the use of other substances.
authors.affiliation: Survey Research Center, Institute for Social Research, University of Michigan, Ann Arbor, MI ramiech@umich.edu.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Miech
authors.affiliation: Survey Research Center, Institute for Social Research, University of Michigan, Ann Arbor, MI.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: O'Malley
authors.affiliation: Survey Research Center, Institute for Social Research, University of Michigan, Ann Arbor, MI.
authors.forename: Lloyd D
authors.initials: LD
authors.lastname: Johnston
authors.affiliation: Survey Research Center, Institute for Social Research, University of Michigan, Ann Arbor, MI.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Patrick
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D066300:Electronic Nicotine Delivery Systems / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D019966:Substance-Related Disorders / Q000453:epidemiology*