Abstract
BACKGROUND: Adults who smoke cigarettes can benefit from switching completely to electronic nicotine delivery systems (ENDS). Research is needed to examine longer-term switching trajectories beyond one year of follow-up. METHODS: This analysis of a previously-described longitudinal cohort study of adults who smoke and purchased JUUL focused on N = 11,153 who completed the 12-month (12 M) follow-up and ≥ 1 of 4 surveys in the second year (Y2; at 15, 18, 21, and 24 months). Outcomes were repeated point prevalence of product use over the past-30-days (P30D) at each Y2 follow-up: repeated point prevalence-switching (i.e., no P30D smoking at any available Y2 follow-ups), repeated point prevalence-smoking, or varying status. Associations between product use status at 12M (switched, exclusive smoking, or dual used) and Y2 product use patterns were examined. RESULTS: Most adults who smoked at baseline and were switched at 12 M reported repeated point prevalence-switching over Y2 (69.5%); repeated point prevalence-smoking was rare (6.2%). In contrast, > 50% of those who were smoking at 12 M (exclusively or with ENDS [JUUL or other brand]) persistently smoked over Y2. Supplementary analyses showed that among adults who exclusively used ENDS at 12 M, those who used ENDS daily were more likely to persistently switch over Y2; similarly, among adults who smoked at 12 M (either exclusively or dual-use with ENDS) those who smoked nondaily were more likely to persistently switch over Y2. Over half of adults who dual used at both 12 M and 24 M substantially reduced (i.e., by 50%+) their baseline cigarette consumption. CONCLUSIONS: For the majority of participants, product use status at 12 M was consistent with use patterns in the second year: most adults who smoked at baseline and were switched at 12 M reported repeated point prevalence-switching over Y2, while any smoking at 12 M- especially daily smoking- was usually followed by repeated point prevalence-smoking. These findings indicate that switching and smoking behavior is generally maintained and remains stable one year after purchasing ENDS.