Any e-cig use among young smokers increases odds of smoking in late adolescence

While it is well-established that youth who initiate nicotine use with e-cigarettes are more likely to start smoking and that e-cigarettes are expanding nicotine addiction, no one had examined whether e-cigarette use promotes continued smoking among youth. Now Brian Kelly and colleagues have published a well-done paper addressing that question: E-cigarette use among early adolescent tobacco cigarette smokers: testing the disruption and entrenchment hypotheses in two longitudinal cohorts. They identified youth who were smoking cigarettes by the time they were 15 in the UK and USA and examined whether any e-cigarette use — even using e-cigarettes a single time — predicted whether the youth would be smoking years later when they reached 18. They found that any e-cigarette use among early adolescent smokers in the UK and USA leads to higher odds of any smoking and more frequent tobacco cigarette use later in adolescence.

This study is important because it debunks the argument that e-cigarettes are diverting youth from smoking cigarettes. Rather, e-cigarette use promotes continued cigarette use. The fact that any e-cigarette use predicts continued smoking is also important because e-cigarette advocates have argued that mere experimentation with e-cigarettes (as opposed to regular use) by youth is not important. This study shows that any use is a problem.

Here is the abstract:

Objective: Using longitudinal data from two large-scale cohorts in the UK and USA, we examine whether e-cigarette use steers adolescent early smokers away from tobacco cigarettes (disruption hypothesis) or deepens early patterns of tobacco smoking (entrenchment hypothesis) in comparison with early smokers who do not use e-cigarettes.

Methods: 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 (n=803) study. In regression models, the focal predictor was lifetime use of an e-cigarette by early adolescence and the primary outcome was current tobacco use by late adolescence (before age 18). Logistic and multinomial models controlled for early adolescent risk factors and sociodemographic background, and were weighted for attrition and adjusted for complex survey designs.

Results: Among youth who were early cigarette smokers, 57% of UK and 58% of US youth also used e-cigarettes. The odds of later adolescent smoking among early smoking youth were significantly higher among e-cigarette users relative to those who had not used e-cigarettes (adjusted OR (AOR_UK)=1.45; AOR_USA=2.19). In both samples, multinomial models indicated that early smoking youth who used e-cigarettes were more likely to be frequent smokers relative to not smoking (AOR_UK=2.01; AOR_USA=5.11) and infrequent smoking (AOR_UK=1.67; AOR_USA=2.11).

Conclusions: Despite national differences in e-cigarette regulation and marketing, there is evidence e-cigarette use among early adolescent smokers in the UK and USA leads to higher odds of any smoking and more frequent tobacco cigarette use later in adolescence.

The full citation is: Kelly BC, Vuolo M, Maggs J, Staff J. E-cigarette use among early adolescent tobacco cigarette smokers: testing the disruption and entrenchment hypotheses in two longitudinal cohorts. Tob Control. 2023 Apr 18:tc-2022-057717. doi: 10.1136/tc-2022-057717. Epub ahead of print. PMID: 37072167. It is available here.