Variations in intensity of e-cigarette use, smoking history, and demographics among past-30-day e-cigarette users
Analyses that examine e-cigarette use often define "users" as those with any past-30-day use; this ignores substantial variations in use patterns, and leads to incorrect perceptions of e-cigarette users. We used data from a national sample of 153,019 U.S. adults (16,987 e-cigarette users), surveyed from online research panels during 2013-2016, to define and describe levels of e-cigarette use based on frequency (days/month) and amount (uses/day). Among adults reporting any past-30-day e-cigarette use, 10 % used on only one day/month, and 28 % used less than weekly (≤4 days); conversely, 22 % used daily or nearly daily (≥27 days/month). Amount of use also varied, with median use being one use/day; >75 % of users reported ≤5 uses/day. Individual characteristics varied substantially among categories of past-30-day users. Daily users were older than non-daily users (43 years versus 36 years; this and all comparisons cited, p<0.005). Young adults (18-24 years) were more likely to report having used e-cigarettes during the past 30 days (OR=1.8), but more likely to have used e-cigarettes on just one day/month (OR=2.2) and to report light levels of use (<5 uses/day) (OR=1.6). Older adults (≥45 years) were more likely to use daily (OR=2.2), and to report ≥10 uses/day (OR=1.8). Although women were less likely to report past-30-day use (OR=0.7), they were more likely than men to use daily (OR=1.4). Overall, >89 % of past-30-day e-cigarette users had been established smokers (100+ cigarettes), and those who used e-cigarettes more frequently were significantly more likely to have quit smoking; 56 % of those reporting ≥10 uses/day were no longer smoking. These data document large variations in frequency and amount of e-cigarette use - associated with different subject characteristics - among past-30-day-users, suggesting that a more discriminating and detailed characterization of users is necessary to understand e-cigarette use.