Role of e-cigarette nicotine concentration in longitudinal transitions between cigarette, e-cigarette and dual use

OBJECTIVE: E-cigarette nicotine concentration level is critical to tobacco regulation. This study seeks to examine whether nicotine level is associated with transitions in tobacco use status such as exclusive cigarette, exclusive electronic (e-)cigarette, dual and no use. METHODS: Using a large, nationally representative cohort from the Population Assessment of Tobacco and Health (PATH) study in the USA, we compared changes in the prevalence of tobacco use status at 1-year follow-up (Wave 7) based on level of e-cigarette nicotine exposure at baseline (Wave 6). Self-reported nicotine concentration was categorised into high (5.0% or more), moderate (1.8-4.9%), low (0.1-1.7%), 0% and 'I don't know'. RESULTS: Among those using e-cigarettes at baseline, those using products containing nicotine (≥0.1%) were more likely to continue exclusive e-cigarette use at follow-up than those using 0% or unknown nicotine content. Among those reporting dual use at baseline, nearly half continued dual use at follow-up regardless of nicotine concentration. However, those using higher nicotine concentrations (≥1.8%) were more likely to either switch to exclusive e-cigarettes or quit entirely indicating greater harm reduction than those using low-nicotine or no-nicotine products. In contrast, nearly half with baseline dual use and 0% nicotine transitioned to exclusive cigarette smoking. CONCLUSION: These findings highlight the complex relationship between e-cigarette nicotine concentration and tobacco use transitions. Regulatory and public health approaches may benefit from balancing the potential harm reduction role of nicotine-containing e-cigarettes for adults who smoke with concerns regarding sustained nicotine dependence and long-term e-cigarette use.