Electronic Cigarette: A Longitudinal Study of Regular Vapers.

Introduction: It is unclear how vaping behavior changes over time in regular vapers, and what occurs when vapers relapse to smoking or when they stop vaping. We assessed change in vaping and smoking behaviors over 12 months in regular vapers.
Methods: A longitudinal study of 3868 regular vapers enrolled on the Internet in 2012-2015 ("baseline"), followed after one (n = 1631, 42%), three (n = 1337, 35%), six (n = 1148, 30%), and 12 months (n = 893, 23%).
Results: Participants had been vaping for a median of five months at baseline. Most (77%) were former smokers, who had not smoked for a median of three months at baseline. Over 12 months, enjoyment gradually became the most frequently cited reason to vape (93%), and vaping to deal with craving for tobacco gradually decreased (from 87% to 56%). In exclusive vapers (ex-smokers), nicotine concentration in e-liquids decreased over time (from 12 to 9 mg/mL), but puffs/day remained stable (200 puffs/day). After 12 months, 9% of 687 former smokers relapsed to smoking and 28% of 64 daily smokers (dual users) stopped smoking. After 12 months, when participants stopped vaping, they tended to relapse to smoking (+18% daily smokers among those who stopped vaping versus -2% in permanent vapers, p < .001). When ex-smokers relapsed to smoking, they tended to stop vaping. Conclusions: After 12 months, enjoyment and relapse prevention were the most important reasons to vape. Rates of relapse to smoking were low in former smokers and quit rates were high in current smokers. Stopping vaping was associated with relapsing to smoking. Implications: Even in established vapers, vaping behavior and reasons to vape change over time. This should be taken into account by clinicians, manufacturers and regulators. Results from this non-representative sample can help generate hypotheses that can later be tested in representative samples of vapers.