Longitudinal data confirms that e-cigarette use promotes transition from experimentation to established smoking

In 2014 Lauren Dutra and I published “Electronic cigarettes and conventional cigarette use among U.S. adolescents: a cross-sectional study,” showing that e-cigarette use was associated with progression from experimenting with cigarettes (kids who had “smoked a puff” of a cigarette) and established smoking (smoked 100 cigarettes).  We got beat up by a lot of e-cigarette enthusiasts because the UCSF press release used the word “gateway,” which they said could only be demonstrated with a longitudinal study that followed kids forward in time.  (The criticisms are at Youth experimentation with e-cigarettes: another interpretation of the data [JAMA. 2014]; Youth tobacco use and electronic cigarettes [JAMA Pediatr. 2014]; Tobacco control policy and electronic cigarettes [JAMA Pediatr. 2014]; Youth tobacco use and electronic cigarettes [JAMA Pediatr. 2014].  Our response is at Youth tobacco use and electronic cigarettes—reply [JAMA Pediatr. 2014])

Ben Chaffee, Shannon Watkins, and I just published that longitudinal study, “Electronic Cigarette Use and Progression From Experimentation to Established Smoking,” in Pediatrics.   Based on the PATH study, kids who had taken a puff on cigarettes but not smoked 100 cigarettes and used e-cigarettes were more likely to have progressed to established smoking (100 cigarettes).

In addition to being valuable in its own right, this is another example of how a well-done cross-sectional study can inform the scientific discussion while we wait for the time to pass needed to do longitudinal studies.  Trying to ignore cross-sectional studies is one of the stalling tactics the e-cigarette enthusiasts are using to avoid the growing case that these products are not “harm reduction.”

Here is the abstract:

BACKGROUND:  It has been shown that never-smoking adolescents who try electronic cigarettes (e-cigarettes) are at increased risk of subsequent conventional cigarette smoking. We evaluated associations between e-cigarette use and progression to established smoking among adolescents who had already tried cigarettes.

METHODS:  Among participants (age 12-17 years) in the nationally representative Population Assessment of Tobacco and Health survey who had smoked a cigarette (≥1 puff) but not yet smoked 100 cigarettes (N = 1295), we examined 3 outcomes at 1-year follow-up as a function of baseline e-cigarette use: (1) having smoked ≥100 cigarettes (established smoking), (2) smoking during the past 30 days, and (3) both having smoked ≥100 cigarettes and past 30-day smoking (current established smoking). Survey-weighted multivariable logistic regression models were fitted to obtain odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for smoking risk factors.

RESULTS: Versus e-cigarette never use, having ever used e-cigarettes was positively associated with progression to established cigarette smoking (19.3% vs 9.7%), past 30-day smoking (38.8% vs 26.6%), and current established smoking (15.6% vs 7.1%). In adjusted models, e-cigarette ever use positively predicted current established smoking (OR: 1.80; 95% CI: 1.04-3.12) but did not reach statistical significance (α = .05) for established smoking (OR: 1.57; 95% CI: 0.99-2.49) and past 30-day smoking (OR: 1.32; 95% CI: 0.99-1.76).

CONCLUSIONS: Among adolescent cigarette experimenters, using e-cigarettes was positively and independently associated with progression to current established smoking, suggesting that e-cigarettes do not divert from, and may encourage, cigarette smoking in this population.

The full citation is:  Chaffee B, Watkins S, Glantz S.  Electronic Cigarette Use and Progression From Experimentation to Established Smoking.  Pediatrics. 2018 Mar 5. pii: e20173594. doi: 10.1542/peds.2017-3594. [Epub ahead of print].  It is available here.