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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
USA PARTICIPANTS: US adolescent population from middle school, with mean age 12.7 (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% 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 (all P<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 (OR:15.78, 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 by far lower in never-smokers compared with ever-smokers. High prevalence of ever marijuana use with e-cigarettes was observed.