Nicotine and tobacco transitions among US youth using electronic nicotine delivery systems: associations with frequency, nicotine dependence, and biomarkers of exposure

Abstract Introduction Vaping nicotine is the most prevalent mode of nicotine use among US youth. Research is needed to understand youth use over time, including transitions to or away from dual use. How these transitions are related to frequency of use, nicotine dependence, and biomarkers of nicotine and tobacco toxicant exposure provides key information on the public health impact of Electronic nicotine delivery system (ENDS) use among US youth. Methods Longitudinal data from Waves 4 and 5 (2016/18 - 2018/19) of the Wave 4 Biomarker Core sample (ages 12-17 at Wave 4) of the Population Assessment of Tobacco and Health Study were used. Eight Wave 4 to 5 transitions in ENDS and combustible tobacco use were examined among youth reporting current ENDS use at Wave 4 (n = 419). Past 30-day ENDS use frequency, nicotine dependence, and biomarkers of nicotine and tobacco toxicant exposure at Wave 4 and Wave 5 were compared across transition groups. Results Youth who maintained dual use and youth who transitioned from dual use to ENDS-only use reported the highest estimated days of ENDS use (M = 22.12 days and 23.86 days, respectively) and the highest mean nicotine dependence (M = 2.75 and 2.74, respectively). Those who maintained dual use had significantly greater increases in nicotine exposure (GMR = 3.87; 95% CI = 1.67, 8.98) and tobacco-specific nitrosamine exposure (GMR = 3.53; 95% CI = 2.19, 5.70) compared to youth who maintained ENDS-only use. Conclusions We found significant heterogeneity by transition group among US youth using ENDS. Dual use, particularly persistent dual use, represents a significant concern for the health of youth. Implications Examining both self-reports of frequency and nicotine dependence as well as biomarkers of nicotine and tobacco toxicant exposure, we found substantial heterogeneity among US youth across different transitions in ENDS use over two years. Our findings suggest that reducing initial dual use among youth should be an important piece of prevention and treatment efforts in order to reduce persistent dual use among youth.