Trends in characteristics and multi-product use among adolescents who use electronic cigarettes, United States 2011-2015.

Evaluate trends from 2011-2015 in electronic cigarette (e-cigarette) use among U.S. adolescents, grades 6-12, including prevalence and associations with past month use of cigarettes and other tobacco products, cigarette smoking intensity, quit attempts, and quit contemplation.Five consecutive waves from the National Youth Tobacco Survey (N = 101,011) were used to estimate the grade- and race/ethnicity-standardized prevalence of past month use of e-cigarettes and nine non e-cigarette tobacco products. We assessed linear trends by year and compared outcomes (e.g., tobacco use, smoking intensity) by e-cigarette past month use.Past month e-cigarette use rose sharply from 2011-2015. In all years and both sexes, e-cigarette past month use and ever use were positively associated with use of cigarettes and other tobacco products, with past month e-cigarette use reaching 52% in 2015 among individuals who used ≥1 non e-cigarette tobacco product in the past month. Meanwhile, from 2011-2015, the population of adolescent past month e-cigarette users increasingly encompassed adolescents who were not past month users of other products (females: 19.0% to 41.7%; males: 11.1% to 36.7%) or had never used other products (females: 7.1% to 13.5%; males: 6.7% to 15.0%). Among male (but not female) past month cigarette users, there was a statistically significant positive association between past month e-cigarette use and daily cigarette smoking but not in all individual years. Past month e-cigarette use among past month cigarette smokers was not associated with cigarette quit attempts or quit contemplation, with no temporal trend.Adolescent past month e-cigarette use is associated with past month use of other tobacco but not with cigarette quit attempts or quit contemplation among cigarette users. Over five years, the average characteristics of U.S. adolescents who use e-cigarettes have shifted, increasingly including more adolescents who do not use non e-cigarette tobacco products