The evidence that e-cigarettes are a gateway for smoking is strong and consistent. Now John Pierce and his colleagues have made that connection even stronger by showing that e-cigarette use strongly predicts daily cigarette smoking. (Previous studies measured current cigarette smoking, meaning in the past 30 days.) Their paper, “Use of E-cigarettes and Other Tobacco Products and Progression to Daily Cigarette Smoking” published in Pediatrics also shows that youth who use more different tobacco products are also much more likely to end up smoking cigarettes every day.
This study has a very strong design; it is a longitudinal study of a nationally representative sample in which the same youth and young adults observed at baseline were followed forward in time for 3 years to see how their product use patterns changed over time. They also controlled for a range of sociodemographic factors that predict tobacco use.
The Conclusions section of the paper provides a nice plain-English summary of the paper:
In this representative sample of US youth and young adults, almost two-thirds had experimented with at least 1 tobacco product and almost one-third experimented with ≥5 tobacco products, of which e-cigarettes and cigarettes were the most popular. Over the 4-year study, 12% reported daily tobacco use, with more than two-thirds of these reporting daily cigarette smoking. Progression to daily cigarette smoking between waves 1 and 4 was 3 times higher among e-cigarette ever users compared with nonusers. Each additional product tried markedly increased the odds of becoming a daily cigarette smoker, as did experimenting with tobacco before age 18 years. These results suggest that recent rapid growth in adolescent e-cigarette use will lead to increased daily cigarette smoking in US young adults.
Indeed, we documented a slowing in the decline of current youth smoking after e-cigarettes came on the market.
While the effects of other (than e-cigarette) tobacco product use also predicted daily smoking, the effect was smaller than the effects of e-cigarette use.
The effects of multiple different product use highlights the importance that tobacco control professionals and regulatory bodies like FDA pay more attention to these other products (hookah, cigarillos, cigars, smokeless tobacco, pipes, snus, kreteks, dissolvables, and bidis) because multiple product use predicts daily smoking, with more product use increasing the chances of daily smoking.
In other words a comprehensive approach to ending all tobacco use is what we need. These products should not be assessed in isolation. Comprehensive flavor bans, taxing all tobacco products as consistent rates, and including all inhaled tobacco products in clean indoor air laws is a good place to start.
Here is the abstract of the paper:
Objectives: To identify predictors of becoming a daily cigarette smoker over the course of 4 years.
Methods: We identified 12- to 24-year-olds at wave 1 of the US Population Assessment of Tobacco and Health Study and determined ever use, age at first use, and daily use through wave 4 for 12 tobacco products.
Results: Sixty-two percent of 12- to 24-year-olds (95% confidence interval [CI]: 60.1% to 63.2%) tried tobacco, and 30.2% (95% CI: 28.7% to 31.6%) tried ≥5 tobacco products by wave 4. At wave 4, 12% were daily tobacco users, of whom 70% were daily cigarette smokers (95% CI: 67.4% to 73.0%); daily cigarette smoking was 20.8% in 25- to 28-year-olds (95% CI: 18.9% to 22.9%), whereas daily electronic cigarette (e-cigarette) vaping was 3.3% (95% CI: 2.4% to 4.4%). Compared with single product triers, the risk of progressing to daily cigarette smoking was 15 percentage points higher (adjusted risk difference [aRD] 15%; 95% CI: 12% to 18%) among those who tried ≥5 products. In particular, e-cigarette use increased the risk of later daily cigarette smoking by threefold (3% vs 10%; aRD 7%; 95% CI: 6% to 9%). Daily smoking was 6 percentage points lower (aRD -6%; 95% CI: -8% to -4%) for those who experimented after age 18 years.
Conclusions: Trying e-cigarettes and multiple other tobacco products before age 18 years is strongly associated with later daily cigarette smoking. The recent large increase in e-cigarette use will likely reverse the decline in cigarette smoking among US young adults.
The full citation for the paper is: Pierce JP, Chen R, Leas EC, White MM, Kealey S, Stone MD, Benmarhnia T, Trinidad DR, Strong DR, Messer K. Use of E-cigarettes and Other Tobacco Products and Progression to Daily Cigarette Smoking. Pediatrics. 2021 Jan 11:e2020025122. doi: 10.1542/peds.2020-025122. Epub ahead of print. PMID: 33431589. It is available here.
In addition, the evidence that e-cigarette use increases the risk of current smoking also keeps piling up. Brittney Keller-Hamilton and colleagues recently published “Electronic cigarette use and risk of cigarette and smokeless tobacco initiation among adolescent boys: A propensity score matched analysis” in Addictive Behaviors (2021; 114: 106770) that reported that “Compared to non-users, [adolescent boys in Ohio who were] e-cigarette users were more than twice as likely to later initiate both cigarette smoking (RR = 2.71; 95% CI: 1.89, 3.87) and SLT [smokeless tobacco] (RR = 2.42; 95% CI: 1.73, 3.38). They were also more likely to become current (i.e., past 30-day) cigarette smokers (RR = 2.20; 95% CI: 1.33, 3.64) and SLT users (RR = 1.64; 95% CI: 1.01, 2.64).”
These studies are also consistent with a meta-analysis published last year that found that e-cigarette use about tripled the odds of future cigarette smoking. This finding of a tripling of risk is, indeed, remarkable consistent. The gateway effect is an established fact.
Of course, even if kids don’t progress to smoking, e-cigarette and other tobacco use is dangerous.