Changing patterns of cigarette and ENDS transitions in the USA: a multistate transition analysis of adults in the PATH Study in 2017–2019 vs 2019–2021

INTRODUCTION: The use of cigarettes and electronic nicotine delivery system (ENDS) has likely changed since 2019 with the rise of pods and disposables, the outbreak of lung injuries related to vaping THC, flavor bans, and the COVID pandemic. We analyzed patterns of initiation, cessation, and transitions between cigarettes, ENDS, and dual use before and after 2019. METHODS: Using the Population Assessment of Tobacco and Health (PATH) Study, we applied a multistate transition model to 28,061 adults in Waves 4–5 (2017–19) and 24,751 adults in Waves 5–6 (2019–21), estimating transition rates for initiation, cessation, and switching products for each period overall and by age group. RESULTS: Cigarette initiation among adults who never used either product decreased from 2017–19 to 2019–21, but ENDS initiation did not significantly change. Persistence of ENDS-only use remained high, with 75–80% still using ENDS only after 1 year. Cigarette-only use transitions remained similar, with about 88% remaining, 7% transitioning to non-current use, and 5% transitioning to dual or ENDS-only use. In contrast, dual use to ENDS-only transitions increased from 9.5% (95%CI: 7.3–11.7%) to 20.1% (95%CI: 17.5–22.7%) per year from 2017–19 to 2019–21, decreasing the persistence of dual use. The dual use to cigarette-only transition remained at about 25%. These changes were qualitatively similar across adult age groups, though adults ages 18–24 years exhibited the highest probability of switching from cigarette-only use to dual use and from dual use to ENDS-only use. CONCLUSIONS: Persistence of ENDS use among adults remained high in 2019–21, but a larger fraction of dual users transitioned to ENDS-only use compared to 2017–19. Because the fraction of cigarette-only users switching to dual use remained low, the public health implications of the increased dual use to ENDS-only transition are minimal.