Prevalence and correlates of electronic-cigarette use in young adults: Findings from three studies over five years.

Background We aimed to examine prevalence and correlates of past-month electronic cigarette (“e-cigarette”) use and use of e-cigarettes to aid a cessation attempt in three samples of young adult smokers recruited online in 2009–2010 (Study 1), 2010–2011 (Study 2), and 2013 (Study 3). Methods Participants were young adults aged 18 to 25 who smoked at least one cigarette in the previous month (Study 1, N = 1987 and Study 2, N = 570) or smoked 3 or more days each week and used Facebook 4 or more days per week (Study 3, N = 79). We examined both past-month e-cigarette use and ever use of e-cigarettes to quit conventional cigarettes. Results Prevalence of past-month use of e-cigarettes was higher in each subsequent study: Study 1 (6%), Study 2 (19%), and Study 3 (41%). In multivariate analyses, significant correlates of past-month e-cigarette use were identified for Study 1 (male sex OR = 2.1, p = .03; past-year quit attempt OR = 1.6, p = .03) and Study 2 (male sex, OR = 1.7, p = .03; younger age OR = 0.88, p = .05), but not Study 3. In multivariate analyses, significant correlates of ever use of e-cigarette to quit conventional cigarettes were identified for Study 1 (education, OR = 1.2, p = .02; smoking within 30 min of waking, OR = 2.8, p = .02; past year quit attempt OR = 4.1, p = .02), and Study 3 (desire to quit smoking, OR = 1.3, p = .02), but not Study 2. Conclusions E-cigarette use is increasingly common among young adults, particularly men. E-cigarette use for quitting conventional cigarettes appears more common among those more nicotine dependent and interested in quitting. [ABSTRACT FROM AUTHOR]