Table 3.

Adult Prevalence and Correlates of E-Cigarette Use

Citation	Data Source	Country	Sample Size	Study Type	Findings
Dockrell et al., 2013	2010 & 2012 Population Survey	Great Britain	2010 – 12,597 including 2,297 cigarette smokers; 2012 – 12,432 including 2,093 cigarette smokers	Cross-Sectional¥	From 2010-2012 • E-cigarette awareness, trial, and current use* more than doubled; • Trial and use occurred most often among current tobacco smokers; • E-cigarette ever-use among tobacco smokers rose from 5.5%-15.0%; • Young respondents (aged 18-34 years) were more likely to report ever-use than older participants (aged ≥55 years); • Daily tobacco smokers more often reported ever-use than occasional smokers; • The most common reason for trying an e-cigarette was to smoke where tobacco was not allowed.
Vickerman et al., 2013	Cigarette quit-line	United States	2,758	Cross-Sectionalŧ	• 30.9% reported e-cigarette ever-use; • 61.7% used them for less than a month; • 9.2% continued to use e-cigarettes at 7-months; • Those who tried e-cigarettes were more likely to be abstinent (30 day point prevalence) at 7-months than those who had not tried them; • More (77.9%) callers who used e-cigarettes for >1 month had multiple quit attempts compared to having one or no attempts (p<0.05); • More callers who never used e-cigarettes (70.2%) also had multiple quit attempts compared to one or no attempts (P<0.05); • The majority of callers who used e-cigarettes for >1 month (58.0%) or used them for < 1 month (63.4%) lived or worked with a tobacco user (p<0.001) when compared to those who never used e-cigarettes;
Adkison et al., 2013	July 2010 – June 2011 International Tobacco Control Survey	U.S. U.K. Canada Australia	5,939 current and former cigarette smokers	Cross-Sectional¥	• Knowledge and ever-use were greatest in countries where products are legal; • ~3% of respondents were current users, and this did not vary by country. • Smokers (vs. nonsmokers), daily smokers (vs. nondaily smokers and quitters), menthol (vs. non-menthol smokers), those who allowed smoking in the home (vs. home smoking ban), and those who took the survey on the web (vs. on the telephone) were more likely to know of e-cigarettes; • Non-daily smokers were more likely than daily smokers to have tried e-cigarettes; • Established quitters were less likely than continuing smokers and those who perceived of e-cigarettes as safer than tobacco were more likely to have tried e-cigarettes; • In the U.S., menthol smokers (vs. non-menthol smokers) and those without a home smoking ban (compared to those with one) were less likely to know of e-cigarettes; • In U.K., smokers (vs. quitters) and those taking the survey on the web (vs. telephone) were more likely to know of e-cigarettes; • In Australia and Canada, those who took the survey on the web (vs. telephone) were more likely to know of e-cigarettes.
King et al., 2013	2010 & 2011 HealthStyles mail and Internet Survey	United States	2010– 6,689 2011– 4.050	Cross-Sectional¥	In 2010 • 38.5% of mail respondents and 40.9% of Internet respondents were aware of e-cigarettes; • 2.1% of mail respondents and 3.3% of internet respondents ever-used e-cigarettes; In 2011 • Awareness rose to 57.9%; • Ever-use rose to 6.2%; • Use was highest among current smokers compared to former and never-smokers.
Li et al., 2013	2011& 2012New Zealand Smoking Monitor	New Zealand	2011– 480 2012– 360	Cross-Sectional¥	Of 480 respondents first surveyed: • 7% had purchased an e-cigarette; • 18-24 year olds were more likely to purchase e-cigarettes than those aged ≥45 years (95% CI 1.17-16.16); Of 360 respondents later surveyed: • 41% reported they would switch to e-cigarettes if they were cheaper than tobacco, with those of low income 3 times more likely to say so (95% CI 1.51-5.88); • 58% said they would use e-cigarettes to help them quit smoking, with those aged 18-24 3 times more likely to say so than those aged ≥45 years (95% CI 1.17-9.69).
Regan et al., 2013	2009& 2010Mail Survey (Consumer-Styles)	United States	2010– 10,587 2011– 0,328	Cross-Sectional¥	From 2009-2010 • E-cigarette awareness rose from 16.4%-32.2%, with increased awareness greatest among current smokers (20.7%-49.6%); • Ever-use rose from 0.6%-2.7%; • Of those who had tried e-cigarettes, 1.2% had used them in the past month; • Ever-use was most common among women, those with lower education, and current tobacco users; • Those with an income <$15,000 who had heard of e-cigarettes were more likely to try them than those earning ≥$60,000; • Blacks and Hispanics were less likely to have heard of e-cigarettes but as likely to have tried e-cigarettes them when compared to Whites.
Pearson et al., 2012	National Survey & Longitudinal Survey	United States	2,649 – online survey¥ & 3,658 longitudinal cohort of tobacco smokersŧ	Cross-Sectionalŧ	In 2010 • 40.2% of on-line respondents were aware of e-cigarettes; • Of on-line respondents, 57.1% of ever-smokers had heard of e-cigarettes (vs. 41.5% of former smokers and 32.5% of never smokers); • In the longitudinal sample, 58.2% of current smokers had heard of e-cigarettes (vs. 57.1% of former smokers); • 11.4% of current smokers used e-cigarettes & 2.0% of former smokers; • Online respondents who indicated quit intent attempt were more likely to use e-cigarettes than those who did not intend or had not attempted to quit; • 70.6% of online respondents and 84.7% of the longitudinal sample thought e-cigarettes were less harmful than tobacco cigarettes. • On-line survey participants perceiving poor health were less likely to have ever-used e-cigarettes than those in good or fair health; • Those intending to quit in the next 6-months were more likely to have ever-used e-cigarettes than those not interested in quitting or who planned to quit in the next 30 days

^*Current Use = Use in the Past 30 Days

^ŧConvenience Sample

^¥Randomly Selected Sample