Conjoint Developmental Trajectories of Adolescent E-cigarette and Combustible Cigarette Use

In this study, we sought to identify which adolescents progress to regular electronic cigarette (e-cigarette) use (without cigarette smoking), which adolescents become dual users of both types of cigarettes, and how dual use develops across time.

Adolescents (N = 1808) from public high schools outside Philadelphia, Pennsylvania, completed in-classroom surveys at wave 1 (fall 2016, beginning of ninth grade) and at 6-month intervals for the following 36 months (fall 2019, beginning of 12th grade).

A sequential processes growth mixture model identified 4 conjoint latent classes: later, rapid e-cigarette uptake (class 1: n = 230); no use of e-cigarettes or combustible cigarettes (class 2: n = 1141); earlier, steady e-cigarette uptake (class 3: n = 265); and dual use of e-cigarettes and combustible cigarettes (class 4: n = 204). Using a rich set of potential risk factors, multinomial logistic regression assessed the likelihood of belonging to each conjoint class compared with the comparison class (dual use). Adolescents in the dual use class were characterized by a greater number and severity of e-cigarette and combustible cigarette risk factors. Adolescents in the 2 e-cigarettes-only classes were characterized by either e-cigarette-specific risk factors (earlier onset) or no risk factors (later onset). The no use class had an absence of risk factors for e-cigarette and cigarette use.

This study provides new prospective evidence for distinct patterns and profiles of adolescents who progress to current e-cigarette use, including adolescents who were initially cigarette smokers. The findings have implications for prevention intervention timing, tobacco product focus, content, and the adolescent subgroups to target.