Abstract
INTRODUCTION: The use of cigarettes and electronic nicotine delivery system (ENDS) has likely changed since 2019 with the rise of pods and disposables, the lung injuries outbreak, flavour bans, Tobacco 21 and the COVID-19 pandemic. METHODS: Using the Population Assessment of Tobacco and Health Study, we applied a multistate transition model to 28 061 adults in waves 4-5 (2017-2019) and 24 584 adults in waves 5-6 (2019-2021), 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 2017-2019 to 2019-2021, but ENDS initiation did not significantly change. The persistence of ENDS-only use remained high (75%-80% after 1 year). Cigarette-only use transitions remained similar (88% remaining, 7% to non-current use and 5% to dual or ENDS-only use). In contrast, dual use to ENDS-only transitions increased from 9.5% (95% CI 7.3% to 11.7%) to 20.0% (95% CI 17.4% to 22.6%) per year, decreasing the persistence of dual use. The dual to cigarette-only use 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: The persistence of ENDS use among adults remained high in 2019-2021, but a larger fraction of dual users transitioned to ENDS-only use compared with 2017-2019. Because the fraction of cigarette-only users switching to dual use remained low, especially among older adults, the public health implications of this change are minimal.