March 7, 2018

Stanton A. Glantz, PhD

Strong evidence for a huge gateway effect for e-cigs in Britain, even stronger than in USA

Strong evidence for a huge gateway effect for e-cigs in England

Recently researchers from England, led by Ann McNeill and including prominent e-cigarette advocates, published a well-done study showing a huge gateway effect for e-cigarettes leading to cigarette smoking among youth in Great Britain.

The paper, “Association between smoking and electronic cigarette use in a cohort of young people,” published in Journal of Adolescent Health, showed that youth who initiated product use with e-cigarettes had 12 times the odds of smoking cigarettes 4 months later than kids who did not use e-cigarettes.

Two strengths of the study are that it is longitudinal (follows the kids forward in time) and controls for a wide range of other risk factors for smoking, including susceptibility to smoking.  The fact that, controlling for susceptibility e-cigarettes have such a huge effect, indicates that (like other studies) e-cigarettes are attracting kids at low risk of initiating nicotine use with conventional cigarettes.

Another impressive thing about the results is that any use of e-cigarettes predicts subsequent any conventional cigarette smoking (even a puff).   While this doesn’t sound like much, another recent paper led by Peter Hajek, “What Proportion of People Who Try One Cigarette Become Daily Smokers,” shows that about two-thirds of kids who take even a puff on a cigarette go on to become daily smokers.

This result shows that the gateway of e-cigarettes in Great Britain is about four times as powerful in Great Britain, where health authorities have embraced e-cigarettes, more than in the US (where most health authorities have been skeptical of e-cigarettes), where the odds of youth who initiate with e-cigarettes progressing to smoking are “only” tripled.  

In the press release on the study minimizing its significance that was issued by ASH UK, ASH pointed out that there is a “two-way association” between e-cigarettes and cigarettes (and there is), but the odds of taking up e-cigarettes after cigarettes were increased by 3.5, a much smaller effect.  While it is true, the direction is dominantly from e-cigarettes to cigarettes.  (This result is similar to a study done at Yale showing that movement from e-cigarettes to cigarettes dominated movement in the opposite direction.)

The authors also tried to minimze the impact of their findings by stating (in the Discussionn section) that "only 4% of never smokers initiated e-cigarette use (vs. 32% of ever smokers)  This suggests that e-cigarettes are attracting few who have never smoked."  This is misleading because there are a lot more never smokers (81.2% of their sample) than ever smokers (19.8% of their sample).  Thus, the prevalence of e-cigarette use generated from never smokers is .04 x .812 = 3.5% and the prevalence of e-cigarette use generated from ever smokers is .32 x .198 = 6.4%.  This means that, of all kids using e-cigarettes, 0.35/(0.35+0.64) = 29% were kids who had never smoked a cigarette.  This is about the same as the fraction of never-smoking kids who were using e-cigarettes that have been found in the other studies.  These kids represent an expansion of the nicotine addiction market.

Here is the abstract:

PURPOSE: Electronic cigarette (e-cigarette) use is associated with smoking initiation among young people; however, it is also possible that smoking is associated with e-cigarette initiation. This study explores these associations among young people in Great Britain.

METHODS: A longitudinal survey of 1,152 11- to 18-year-olds was conducted with baseline in April 2016 and follow-up between August and October 2016. Logistic regression models and causal mediation analyses assessed whether (1) ever e-cigarette use and escalation were associated with smoking initiation (ever smoking at follow-up) among baseline never smokers (n = 923), and (2) ever smoking and escalation were associated with e-cigarette initiation (ever e-cigarette use at follow-up) among baseline never e-cigarette users (n = 1,020).

RESULTS: At baseline, 19.8% were ever smokers and 11.4% were ever e-cigarette users. Respondents who were ever e-cigarette users (vs. never users, 53% vs. 8%, odds ratio [OR] = 11.89, 95% confidence interval [CI] = 3.56-39.72) and escalated their e-cigarette use (vs. did not, 41% vs. 8%, OR = 7.89, 95% CI = 3.06-20.38) were more likely to initiate smoking. Respondents who were ever smokers (vs. never smokers, 32% vs. 4%, OR = 3.54, 95% CI = 1.68-7.45) and escalated their smoking (vs. did not, 34% vs. 6%, OR = 5.79, 95% CI = 2.55-13.15) were more likely to initiate e-cigarette use. There was a direct effect of ever e-cigarette use on smoking initiation (OR = 1.34, 95% CI = 1.05-1.72), and ever smoking on e-cigarette initiation (OR = 1.08, 95% CI = 1.01-1.17); e-cigarette and smoking escalation, respectively, did not mediate these effects.

CONCLUSIONS: Among young people in Great Britain, ever e-cigarette use is associated with smoking initiation, and ever smoking is associated with e-cigarette initiation.

The citation is: East K, Hitchman S, Bakolis I, Williams S, Cheeseman H, Arnott D, McNeill A. Association Between Smoking and Electronic Cigarette Use in a Cohort of Young People. J Adolesc Health. 2018 Feb 21. pii: S1054-139X(17)30903-5. doi: 10.1016/j.jadohealth.2017.11.301. [Epub ahead of print].  It is available here.

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