Abstract
IMPORTANCE: The US Food and Drug Administration's Center for Tobacco Products (CTP) prioritized its enforcement efforts against nontobacco, nonmenthol (ie, sweet)-flavored cartridge e-cigarettes in February 2020. Within-person e-cigarette initiation, continuation, and switching behaviors among youth are unknown following CTP's prioritized enforcement efforts. OBJECTIVE: To describe transitions in youths' e-cigarette flavor/device combination use, brand use, nicotine use, and frequency of use following CTP's e-cigarette enforcement prioritization. DESIGN, SETTING, AND PARTICIPANTS: The US population-based, nationally representative Population Assessment of Tobacco and Health cohort study included data collected in 2019 and 2021 from youth aged 12 to 17 years. The data were analyzed from February to June 2023. EXPOSURE: e-cigarette use (past 30 days), flavor/device combination used, brand used, nicotine use, and frequency of use. MAIN OUTCOMES AND MEASURES: Transitions in e-cigarette use, flavor/device combination used, brand used, nicotine use, and frequency of use between 2019 and 2021 among 9088 youth aged 12 to 17 years in 2019; prevalence of e-cigarette use, flavor/device combination used, and brand used in 2019 (n = 8771) and 2021 (n = 5574) among youth aged 14 to 17 years in each year. RESULTS: The 2019 sample included 8771 youth. The population of those aged 12 to 17 years was 49.0% female (95% CI, 48.7%-49.3%) and 51.0% male (95% CI, 50.8%-51.3%). Participants were 15.4% Black (95% CI, 15.0%-15.7%), 24.1% Hispanic (95% CI, 23.9%-24.4%), 75.9% non-Hispanic (95% CI, 75.6%-76.1%), 69.1% White (95% CI, 68.5%-69.8%), and 15.5% another race (95% CI, 14.9%-16.1%). Among youth ages 12 to 17 years who did not use e-cigarettes in 2019, 531 (6.5%) initiated use in 2021 (95% CI, 5.9%-7.1%); among them, 415 (76.8%) initiated with a combination other than a sweet cartridge (95% CI, 72.2%-80.8%). Among youth ages 12 to 17 who used e-cigarettes in 2019, 360 (47.8%) continued use in 2021 (95% CI, 44.0%-51.1%). Continuation rates were similar for those who used sweet-cartridge e-cigarettes (144 [51.5%]; 95% CI, 45.7%-57.3%) and those who used other combinations (204 [47.6%]; 95% CI, 42.8%-52.4%) in 2019. Among those who continued e-cigarette use in 2021, 121 (84.0%) of those who used sweet-cartridge e-cigarettes in 2019 switched to a different combination (95% CI, 77.0%-89.2%). Overall, among youth who used e-cigarettes in 2021, 177 (53%) used a sweet-disposable combination, 32 (11%) used a sweet-cartridge, and no individual brand was used by more than 10%. CONCLUSIONS AND RELEVANCE: The results of this longitudinal cohort study of youth in the US suggest that most youth who initiated or continued e-cigarette use in 2021 used flavor/device combinations that were excluded from CTP's enforcement priorities. Restrictions and enforcement efforts that only cover a subset of products may be ineffective at preventing youth flavored e-cigarette use.