Smoking Trajectories of Adult Never Smokers 12 Months after First Purchase of a JUUL Starter Kit.

We assessed adult never smokers' trajectories of smoking over 12 months after a first-time JUUL Starter Kit (JSK) purchase. Adult (≥ 21) never smokers (N = 3853) who purchased a JSK were recruited into an observational naturalistic study. Analyses distinguished those who had previously used ENDS (NS+E, N = 2848) from those who had not (NS-NE, N = 1005). Participants were invited to complete follow-up assessments at 1, 2, 3, 6, 9, and 12 months. "Smoking" was defined as any past-30-day smoking ("even a puff"). Past-30-day smoking was reported by 5.01% of NS+E at month one, and 7.56% at month 12; for NS-NE, these were 10.23% and 12.35%. In both groups, < 5% reported smoking at both 9 and 12 months. Across follow-ups, 25%-49% of those reporting having smoked then said they were now smoking "not at all"; the remainder reported low frequency (10-12 days-per-month) and quantity (2-4 cigarettes-per-day) of smoking. Past-30-day use of JUUL remained at ≥ 80% across follow-ups. Each additional day-per-month of JUUL use decreased the odds of smoking by 1%. Some adult never smokers who purchased a JSK reported smoking during the suceeding year; smoking was light and intermittent. Participants who used JUUL more frequently were less likely to smoke.