title: Electronic cigarette and marijuana use among youth in the United States.
abstract: There are growing concerns over the high rate of electronic cigarette (e-cigarette) use and decreases in perceived harm of marijuana use among youth. We seek to identify risk factors associated with e-cigarette and marijuana use among U.S. middle and high school students.
  
  
  
  Estimates of e-cigarette use only, marijuana use only, dual use of both substances as well as frequency of substance use were calculated for 8th, 10th and 12th grades with the typical age of 13, 15, 17 years old respectively by using the 2014 Monitoring the Future survey (n=16,184).
  
  
  
  Overall, 7.9% of students only used e-cigarettes, 9.3% of students only used marijuana, and 6.6% of students used both e-cigarettes and marijuana in the last 30days. E-cigarette use only was most prevalent among 8th and 10th graders while marijuana use only was most prevalent among 12th graders. The dual use of e-cigarettes and marijuana rapidly increased from 8th graders (2.6%) to 10th graders (7.3%) and maintained a high level for 12th graders (8.5%). Students' sociodemographic factors, school performance and work intensity were associated with e-cigarette and marijuana use in the multivariate analysis. Being a dual user of e-cigarettes and marijuana was associated with increased risk of a medium level or a high level of e-cigarette use and a medium level of marijuana use CONCLUSIONS: This study raised the possibility that youth start to use e-cigarettes at an earlier age and then progress to other substances. Education campaigns with tailored messages to prevent youth from vaping and drug use are critically needed.
authors.affiliation: Health Services & Outcomes Research, Children's Mercy Hospital, Kansas City, MO, United States; Department of Biomedical & Health Informatics, University of Missouri-Kansas City, United States; Department of Pediatrics, University of Missouri-Kansas City, United States. Electronic address: hdai@cmh.edu.
authors.forename: Hongying
authors.initials: H
authors.lastname: Dai
authors.affiliation: Bellevue University, Omaha, NE, United States.
authors.forename: Jianqiang
authors.initials: J
authors.lastname: Hao
mesh_terms: D000041:Absenteeism; D000073978:Academic Performance / Q000706:statistics & numerical data; D000293:Adolescent; D003430:Cross-Sectional Studies; D066300:Electronic Nicotine Delivery Systems / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D000074609:Marijuana Use / Q000453:epidemiology*; D015999:Multivariate Analysis; D015995:Prevalence; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology
keywords: Dual use; E-cigarette; Frequency of use; Marijuana; Monitoring the Future survey; Youth