Vaping Among Young Smokers Tied to Higher Cigarette Use in Later Adolescence

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Findings from 2 large-scale, nationally representative cohorts in the US and UK show that among early tobacco smokers, vaping in early adolescence increased the likelihood of smoking tobacco cigarettes later in adolescence.

Among youths who smoked tobacco cigarettes by early adolescence (before age 15), the odds of later adolescent smoking (before age 18) were significantly higher for those who used e-cigarettes relative to those who had not used e-cigarettes, both in the UK (adjusted OR 1.45, 95% CI 1.05-2.01) and the US (aOR 2.55, 95% CI 1.59-4.08) cohorts, reported authors in the journal Tobacco Control.

"Youth in the USA and the UK show similar long-term declines in tobacco cigarette smoking and recent increases in e-cigarette use, although with stronger shifts towards vaping among US youth," wrote corresponding author Jeremy Staff, PhD, of Pennsylvania State University in University Park, and colleagues. "Yet, while numerous studies suggest that e-cigarettes in adolescence may be a catalyst for later tobacco use, less well considered is how vaping may shape tobacco consumption among youth who have already initiated smoking tobacco cigarettes early in adolescence."

To explore how vaping affects tobacco use over time among adolescents who were early initiates into smoking, Staff and colleagues tested 2 competing hypotheses:

• Disruption: Vaping steers adolescent early smokers away from tobacco cigarettes towards exclusive use of e-cigarettes.
• Entrenchment: Vaping increases the odds of continuation of nicotine use and increases the frequency of tobacco cigarette smoking.

A total of 1893 youth who smoked tobacco cigarettes by early adolescence (before age 15) were selected from the ongoing UK Millennium Cohort Study (n=1090) and the US Population Assessment of Tobacco and Health (PATH) Study (n=803). Participants in both cohorts were regularly surveyed about their use of e-cigarettes and how often they smoked conventional cigarettes before they reached the age of 18 years.

Among early adolescent smokers, the prevalence of early use of e-cigarettes was nearly the same in the MCS (57%) and the PATH (58%) cohorts.

In both cohorts, multinomial models indicated that early smokers who used e-cigarettes were more likely to be frequent smokers relative to not smoking (aOR_UK 2.01, 95% CI 1.33-3.05; aOR_US 5.11, 95% CI, 2.73-9.55) and infrequent smoking (aOR_UK 1.67, 95% CI 1.06-2.63; aOR_US 2.11, 95% CI, 1.03-4.34). For the purposes of the study, frequent smoking was defined as "usually smoked more than six cigarettes per week" in the MCS cohort or ≥27 cigarettes in the previous month in the PATH cohort.

These findings supported the entrenchment hypothesis, stated researchers, “namely that e-cigarettes entrenched teens who smoked early into later patterns of continued and more frequent tobacco use.”

In contrast, researchers did not find any evidence that use of e-cigarettes disrupted tobacco cigarette smoking in early smokers. In the US cohort, 42% of early e-cigarette users continued smoking in late adolescence, while only 24% of participants who did not use e-cigarettes later smoked. Among UK participants, 61% of early e-cigarette users continued to smoke in late adolescence, compared with 50% of smokers who did not use e-cigarettes, according to the study results.

Also of note was that in both MCS and PATH cohorts, early smokers who did not use e-cigarettes were more likely to report no nicotine use of either type in late adolescence (46% in MCS and 64% of PATH youth vs 31% and 34%, respectively, for youth who used e-cigarettes).

"Youth potentially face considerable health and economic costs from tobacco smoking and are in need of interventions for e-cigarette use. Youth in these cohorts were the first generation to be exposed as adolescents to e-cigarettes as a new nicotine delivery product ('guinea pig generation')," wrote investigators.

"Among youth who started smoking early in adolescence, early e-cigarette adopters were more likely to become entrenched into tobacco use and in heavier smoking than those who smoked but had not used e-cigarettes. Tobacco control efforts aimed at adolescents should incorporate the risks posed by e-cigarettes for early smoking youth,” continued Staff et al.

Investigators noted some limitations to their study, including the observational nature of their investigation which did not allow them to infer that e-cigarette use combined with smoking played a causal role in entrenching smoking behavior.

Reference: Staff J, Kelly BC, Vuolo M, Maggs J. E-cigarette use among early adolescent tobacco cigarette smokers: Testing the disruption and entrenchment hypotheses in two longitudinal cohorts. Tob Control. Published online April 18, 2023. doi:10.1136/tc-2022-057717.