Changes in dependence over one year among US adults who smoke cigarettes and switched completely or partially to use of the JUUL-brand electronic nicotine delivery system.

Background: Electronic nicotine delivery systems (ENDS) are substitute sources of nicotine for adults who smoke cigarettes. Understanding changes in dependence as people switch from cigarettes to ENDS is relevant to public health. This study assessed changes in dependence among adults who switched completely or partially (dual users) from cigarettes to JUUL-brand ENDS over 12 months.

Methods: US adults who smoke and purchased a JUUL Starter Kit ( = 17,619) completed a baseline assessment and were invited to 1-, 2-, 3-, 6-, 9- and 12-month follow-ups. Dependence on cigarettes at baseline and on JUUL at follow-ups was assessed with the Tobacco Dependence Index (TDI; Range 1-5). Analyses estimated the minimal important difference (MID) for the scale, compared JUUL dependence to baseline cigarette dependence and assessed changes in JUUL dependence over 1-year, including among those using JUUL at all follow-ups.

Results: Participants who switched at month 2 had month 1 JUUL TDI scores 0.24 points greater than those who continued smoking (<0.001); thus MID=0.24. Among both switchers and dual users overall, dependence on JUUL 1 and 12 months later was lower than baseline dependence on cigarettes (s<0.001); participants who smoked every day showed more consistent and larger reductions. Among participants who persistently used JUUL without smoking, dependence increased 0.01 points per month (<0.001), but was leveling off over time.

Conclusions: Dependence on JUUL was lower than baseline cigarette dependence. Increases in JUUL dependence were small over 12 months of continual JUUL use. These data indicate that ENDS, including JUUL, have lower dependence potential than cigarettes.