RT Journal Article SR Electronic T1 Initiation of any tobacco and five tobacco products across 3 years among youth, young adults and adults in the USA: findings from the PATH Study Waves 1–3 (2013–2016) JF Tobacco Control JO Tob Control FD BMJ Publishing Group Ltd SP s178 OP s190 DO 10.1136/tobaccocontrol-2019-055573 VO 29 IS Suppl 3 A1 Cassandra A Stanton A1 Eva Sharma A1 Elizabeth L Seaman A1 Karin A Kasza A1 Kathryn C Edwards A1 Michael J Halenar A1 Kristie A Taylor A1 Hannah Day A1 Gabriella Anic A1 Lynn C Hull A1 Maansi Bansal-Travers A1 Jean Limpert A1 Lisa D Gardner A1 Hoda T Hammad A1 Nicolette Borek A1 Heather L Kimmel A1 Wilson M Compton A1 Andrew Hyland YR 2020 UL http://tobaccocontrol.bmj.com/content/29/Suppl_3/s178.abstract AB Objective This study reports weighted cross-sectional prevalence of never use of tobacco, and longitudinal past 12-month (P12M), past 30-day (P30D) and frequent P30D any tobacco or specific tobacco product initiation across three 1-year waves. Longitudinal three-wave pathways are examined to outline pathways of exclusive and polytobacco initiation, as well as pathways of new initiators of electronic nicotine delivery systems (ENDS) or cigarettes.Design Data were drawn from the first three waves (2013–2016) of the Population Assessment of Tobacco and Health Study, a nationally representative, longitudinal cohort study of US youth and adults. Respondents with data at all three waves (youth, N = 11 046; young adults, N = 6478; adults 25+, N = 17 188) were included in longitudinal analyses.Results Across the three age groups, weighted cross-sectional analyses revealed never any tobacco use decreased each year from 2013 to 2016, reflecting overall increases in tobacco initiation in the population during this time. Compared with cigarettes, cigars, hookah and smokeless tobacco, ENDS had the highest proportion of P12M initiation from Wave 1 to Wave 3 (W3) for each age group. Among youth Wave 2 P30D initiators of exclusive ENDS or cigarettes, the most common W3 outcome was not using any tobacco (ENDS: 59.0% (95% CI 48.4 to 68.8); cigarettes: 40.3% (95% CI 28.7 to 53.1)).Conclusions Initiation rates of ENDS among youth and young adults have increased the number of ever tobacco users in the US prevention strategies across the spectrum of tobacco products which can address youth initiation of tobacco products.