Changes from 2017 to 2018 in e-cigarette use and in ever marijuana use with e-cigarettes among US adolescents: analysis of the National Youth Tobacco Survey

Aims To examine changes from 2017 to 2018 in e-cigarette use and ever marijuana use with e-cigarettes among US adolescents. Design Analysis of data from the 2017 and 2018 National Youth Tobacco Survey (NYTS), cross-sectional surveys of US middle school (grades 6-8) and high school (grades 9-12) students. Setting United States. Participants US adolescent population from middle school, with mean age = 12.7 [standard deviation (SD) = 1.0] years, and high school, with mean age = 16.1 (SD = 1.3) years. Measurements Analysis of e-cigarette use and ever use of marijuana with e-cigarettes according to frequency of use and smoking status, comparing 2017 with 2018. Frequent smoking and e-cigarette use was defined as use for >= 20 of the past 30 days. Findings Past 30 days e-cigarette use was reported by 33.1% [95% confidence interval (CI) = 29.1-37.4%] of ever/no past 30 days smokers, 68.6% (95% CI = 64.1-72.7%) of past 30 days smokers and 7.2% (95% CI = 6.3-8.2%) of never smokers in 2018 and by 19.3% (95% CI = 16.1-23.1%), 53.0% (95% CI = 46.9-58.9%) and 3.3% (95% CI = 2.7-4.4%) in 2017, respectively (allP < 0.001). Prevalence of past 30 days e-cigarette use was higher among frequent smokers (69.8%, 95% CI = 62.3-76.5% in 2018; 53.8%, 95% CI = 44.1-63.2% in 2017,P < 0.001) and lower among never smokers. Most of the latter were infrequent users, while frequent and daily e-cigarette use was 18- and 24-fold lower compared with ever smokers, respectively. Approximately half of past 30 days and 70% of frequent e-cigarette users reported ever marijuana use with e-cigarettes in both years. Past 30 days smokers were more likely to report past 30 days e-cigarette use [odds ratio (OR) = 15.79, 95% CI = 12.58-19.83 in 2018; OR = 16.11, 95% CI = 12.44-20.86 in 2017) compared with adolescents reporting no past 30 days smoking. Conclusions Among US adolescents, e-cigarette use increased in all smoking groups in 2018 compared with 2017. Frequent and daily e-cigarette use was far lower in never-smokers compared with ever-smokers. High prevalence of ever marijuana use with e-cigarettes was observed.