Changing patterns of cigarette and ENDS transitions in the US: a multistate transition analysis of youth and adults in the PATH Study in 2015–17 vs 2017–2019

Introduction It is unknown how recent changes in the tobacco product marketplace have impacted transitions in cigarette and electronic nicotine delivery system (ENDS) use. Methods A multistate transition model was applied to 24,242 adults and 12,067 youth in Waves 2–4 (2015–2017) and 28,061 adults and 12,538 youth in Waves 4–5 (2017–2019) of the Population Assessment of Tobacco and Health (PATH) Study. Hazards for initiation, cessation, and product transitions were estimated in multivariable models, accounting for gender, age group, race/ethnicity, and daily vs non-daily product use. Results Changes in ENDS initiation/relapse rates from never, non-current, and cigarette-only use depended on age group, including among adults. Among youth never users, the 1-year probability of ENDS initiation increased after 2017 from 1.6% (95%CI: 1.4-1.8%) to 3.8% (95%CI: 3.4-4.2). Persistence of ENDS-only use (1-year probability of remaining an ENDS-only user) increased for youth from 40.7% (95%CI: 34.4-46.9%) to 65.7% (95%CI: 60.5-71.1%) and for adults from 57.8% (95%CI: 54.4-61.3%) to 78.2% (95%CI: 76.080.4%). Persistence of dual use similarly increased for youth from 48.3% (95%CI: 37.4-59.2%) to 60.9% (95%CI: 43.0-78.8%) and for adults from 40.1% (95%CI: 37.0-43.2%) to 63.8% (95%CI: 59.6-67.6%). Youth and young adult dual users became more likely to transition to ENDS-only use but middle-aged and older adults did not. Conclusions ENDS and dual use have become more persistent. Middle-aged and older adult dual users have become less likely to transition to cigarette-only use but not more likely to discontinue cigarettes. Youth and young adults are more likely to transition to ENDS-only use. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This project was funded through National Cancer Institute (NCI) and Food and Drug Administration (FDA) grant U54CA229974. The opinions expressed in this article are the authors' own and do not reflect the views of the National Institutes of Health, the Department of Health and Human Services, or the United States government. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Institutional Review Board of the University of Michigan exempted this work from human subjects regulation (HUM00162265). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Public Use Files from the PATH study are available for download from an open access repository (). Restricted-Use Files ([https://doi.org/ 10.3886/ICPSR36231.v31][1]) require a Restricted Data Use Agreement. Conditions of use are available on the websites above. [1]: https://doi.org/10.3886/ICPSR36231.v31