Cigarette and ENDS dual use longitudinal transitions among adults in the Population Assessment of Tobacco and Health (PATH) Study, Waves 4-5 (2016-2019).

Introduction: The study assessed longitudinal transitions among adult (18 and older) past 30-day daily and non-daily dual users of cigarettes and electronic nicotine delivery systems (ENDS).

Methods: Using data from Wave 4 (W4; 2016/17) and Wave 5 (W5; 2018/19) of the Population Assessment of Tobacco and Health (PATH) Study, a nationally representative, longitudinal cohort study of US adults, multivariable regressions were conducted among W4 dual users of cigarettes and ENDS to examine past 30-day cigarette smoking at W5. The study also analyzed changes in frequency of past 30-day smoking and cigarettes smoked per day between W4 and W5, stratified by W4/W5 daily/non-daily ENDS use among W4 daily and non-daily cigarette smokers.

Results: Among W4 dual users, those smoking daily and using ENDS non-daily had higher odds of daily cigarette smoking at W5 than daily users of both products (AOR: 2.32, 95 % CI: 1.38-3.90). W4 daily smokers who used ENDS daily at Wave 5 smoked cigarettes on fewer days at Wave 5 than W4 daily smokers who were either daily ENDS users at Wave 4 (B = -4.59; SE = 1.43, p < 0.01) or non-daily ENDS users at Wave 4 (B = -4.55; SE = 1.24, p < 0.001). Among W4 non-daily cigarette smokers, W4 non-daily ENDS users who used daily at W5 smoked cigarettes on fewer days (B = -4.04, SE = 1.82) at W5 than those who were non-daily ENDS users at W4 and W5.

Conclusions: Findings highlight the importance of frequency of ENDS use in reducing cigarette smoking and could inform smoking cessation interventions among daily cigarette smokers.