November 5, 2015

Stanton A. Glantz, PhD

Putting the recent Yale study of e-cigarette minimum purchase age laws into context

The recent paper “How does electronic cigarette access affect adolescent smoking” by Yale University economist Abagail Friedman [1] has attracted a lot of attention from e-cigarette advocates (see links at the end of this post) because of its conclusion that “Across the board … reducing e-cigarette access increases smoking among 12 to 17 year olds.”
 
The paper correlated cigarette use in six national cross-sectional (“snapshot”) survey waves of cigarette use collected between 2002 and 2013 with whether or not the respondents lived in states covered by laws restricting sales of e-cigarettes to kids.  The paper showed declining cigarette use in all states, but after the laws passed, the levels of (declining) smoking were higher than predicted levels without the law.
 
In interpreting the results in this paper, it is important to keep in mind what it did not include in the analysis: e-cigarette use.  As Dr. Friedman noted in her paper, “this analysis does not measure electronic cigarette use, and thus cannot speak to shifts in that behavior or its long run effects.”  She also took care to note that the market had not yet reached equilibrium, which is particularly important when thinking about kids and e-cigarettes.
 
Because the market is still evolving, it is important to consider how e-cigarette use interacts with cigarette smoking [2].  Viewed in this context, a more complete interpretation of the findings is not that these laws are “increasing teen smoking” but that reduced access to e-cigarettes is associated with fewer kids initiating nicotine addiction with e-cigarettes.
 
The paper does not address e-cigarette use (because that information was not available in the dataset that was used) or whether kids are simply substituting e-cigarettes for cigarettes (as harm reduction enthusiasts would hope) or whether e-cigarettes are expanding nicotine use, but there are several other studies that do examine these issues.
 
While some kids who are initiating nicotine use with e-cigs have similar risk profiles as cigarette smoking youth, many have risk profiles that make them unlikely to initiate nicotine use before e-cigarettes existed .  In particular, Wills et al [3] found that “People who used only e-cigarettes did not score high on
variables such as rebelliousness, sensation seeking, and peer smoker affiliations compared with dual users.”
 
And once kids initiate nicotine use with e-cigarettes, they are likely to go on to smoke cigarettes.  Among ninth grade never cigarette smokers in Los Angeles, nonsmoking kids who started nicotine with e-cigarettes were almost three times as likely as never e-cigarette users to report smoking 6 and 12 months later (average effect across time points: AOR=2.73, 95%CI: 2.00-3.73) [4].  Similarly, longitudinal data on a national sample of youth and young adults aged 16 to 26  who started nicotine use with e-cigarettes users were eight times more likely than never e-cigarette users to be smoking one year later (AOR=8.3, 95%CI: 1.2-58.6) [5].  The same study showed that among those who had not started smoking cigarettes, e-cigarette users had increased susceptibility to becoming smokers in the future compared to those who did not use e-cigarettes (AOR=8.5, 95%CI: 1.3-57.2).
 
These two longitudinal studies are consistent with earlier cross-sectional studies on the relationship between e-cigarette use and smoking. Middle and high school e-cigarette users who experimented with cigarettes are more likely to be established smokers [6].  High school [7]  and young adult (18 to 29 year old) e-cigarette users are more willing and open to smoking cigarettes, and middle and high school e-cigarette users in the U.S. [8] and 10 and 11 year old e-cigarette users in Wales [9] are more likely to intend to smoke in the future than those who do not use e-cigarettes.
 
It may be that the short time during which the laws were on the books simply did not allow enough time for these effects to be manifest in Friedman’s analysis (something she cautions about in the paper). 
 
There are also some technical concerns that the statistical model may be “overspecified,” which could lead to erroneous estimates, as well as the fact that the model assumes a constant unchanging shift in smoking behavior after the laws were passed.  Another concern is that the analysis did not detect an effect of smokefree laws on youth smoking, something that has been demonstrated in many earlier studies [10-13] In addition, only including state-level smoke-free laws (as Friedman did) likely creates misclassification of smoke-free law coverage because the strongest laws are often enacted at the local level [11].  The analysis also does not consider time-varying factors that may have occurred contemporaneously with the e-cigarette youth access laws, such as e-cigarette prices which may have been lower than cigarette prices from 2009-2012 [14].  
 
It is worth noting that some of the same e-cigarette advocates who loudly complained that you cannot draw “causal” conclusions based on cross-sectional data when we published our study [6] showing that kids who experimented with cigarettes and ever used e-cigarettes were six (OR=6.31, 95%CI: 5.39-7.39) times as likely to have become established smokers as those who had never used e-cigarettes have embraced the causal language in the Friedman study, which is an analysis of repeated cross-sectional data.
 
Assuming that the technical issues noted above do not turn out to be serious problems, this new paper indicates that, as overall cigarette use continues to fall, e-cigarette youth access controls are associated with relatively fewer kids initiating nicotine use with cigarettes.  It does not say anything about the effects of e-cigarette youth access laws on total nicotine use, which other studies show has increased as a result of the advent and aggressive marketing of e-cigarettes [15], and the eventual level of cigarette smoking among youth and young adults that result from this increased use of addictive nicotine delivery products.
 
Finally, any nicotine use by kids is a bad thing. 
 
The bottom line:  Until and unless there is convincing evidence from a range of studies showing that e-cigarettes are leading to less, not more, nicotine addiction, current laws policies designed to discourage e-cigarette use among kids, including minimum age of sales, including e-cigarettes in clean indoor air laws, and banning marketing targeting kids, should continue to be promoted.
 
References
1.            Friedman A. How does Electronic Cigarette Access affect Adolescent Smoking? Journal of health economics. 2015. http://dx.doi.org/10.1016/j.jhealeco.2015.10.003
2.            Kalkhoran S, Glantz SA. Modeling the Health Effects of Expanding e-Cigarette Sales in the United States and United Kingdom: A Monte Carlo Analysis. JAMA internal medicine. 2015 Oct 1;175(10):1671-80. http://www.ncbi.nlm.nih.gov/pubmed/26322924
3.            Wills T, Knight R, Williams R, et al. Risk factors for exclusive e-cigarette use and dual e-cigarette use and tobacco use in adolescents. Pediatrics. 2015;135(1):e43-e51.
4.            Leventhal AM, Strong DR, Kirkpatrick MG, et al. Association of Electronic Cigarette Use With Initiation of Combustible Tobacco Product Smoking in Early Adolescence. Jama. 2015 Aug 18;314(7):700-7. http://jama.jamanetwork.com/article.aspx?articleid=2428954
5.            Primack BA, Soneji S, Stoolmiller M, et al. Progression to Traditional Cigarette Smoking After Electronic Cigarette Use Among US Adolescents and Young Adults. JAMA pediatrics. 2015 Sep 8:1-7. http://www.ncbi.nlm.nih.gov/pubmed/26348249
6.            Dutra LM, Glantz SA. Electronic cigarettes and conventional cigarette use among US adolescents a cross-sectional study. JAMA pediatrics. 2014;168(7):684. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142115/
7.            Wills TA, Sargent JD, Knight R, et al. E-cigarette use and willingness to smoke: a sample of adolescent non-smokers. Tobacco control. 2015 Aug 10. http://tobaccocontrol.bmj.com/content/early/2015/08/10/tobaccocontrol-2015-052349.abstract
8.            Bunnell RE, Agaku IT, Arrazola R, et al. Intentions to smoke cigarettes among never-smoking U.S. middle and high school electronic cigarette users, National Youth Tobacco Survey, 2011-2013. Nicotine & Tobacco Research. 2014 August 20, 2014. http://ntr.oxfordjournals.org/content/early/2014/08/18/ntr.ntu166.abstract
9.            Moore GF, Littlecott HJ, Moore L, et al. E-cigarette use and intentions to smoke among 10-11-year-old never-smokers in Wales. Tobacco control. 2014 Dec 22. http://www.ncbi.nlm.nih.gov/pubmed/25535293
10.          Wasserman J, Manning WG, Newhouse JP, et al. The effects of excise taxes and regulations on cigarette smoking. Journal of health economics. 1991 May;10(1):43-64. http://www.ncbi.nlm.nih.gov/pubmed/10112149
11.          Song AV, Dutra LM, Neilands TB, et al. Association of Smoke-Free Laws With Lower Percentages of New and Current Smokers Among Adolescents and Young Adults: An 11-Year Longitudinal Study. JAMA pediatrics. 2015 Sep 8;169(9):e152285. http://www.ncbi.nlm.nih.gov/pubmed/26348866
12.          Shang C. The effect of smoke-free air law in bars on smoking initiation and relapse among teenagers and young adults. International journal of environmental research and public health. 2015 Jan;12(1):504-20. http://www.ncbi.nlm.nih.gov/pubmed/25584419
13.          Chaloupka F, Grossman M. Prices, Tobacco Control Policies and Youth Smoking. 1996.
14.          Huang J, Tauras J, Chaloupka FJ. The impact of price and tobacco control policies on the demand for electronic nicotine delivery systems. Tobacco control. 2014;23(suppl 3):iii41-iii7. http://dx.doi.org/10.1136/tobaccocontrol-2013-051515
15.          Duke JC, Lee YO, Kim AE, et al. Exposure to electronic cigarette television advertisements among youth and young adults. Pediatrics. 2014 Jul;134(1):e29-36. http://pediatrics.aappublications.org/content/134/1/e29.long
 
Examples of how e-cigarette advocates are describing the Friedman study:
 
http://vaperanks.com/yale-study-finds-youth-e-cigarette-bans-lead-to-inc...
http://www.vapeshop411.com/are-e-cig-bans-to-minors-working-2/
https://www.planetofthevapes.co.uk/news/vaping-news/2015-11-03_truth-and...
http://spinfuel.com/e-cigarette-teen-smoking/
Brad Rodu and Gil Ross quoted: http://www.journalnow.com/news/local/yale-study-finds-state-youth-e-cig-...
Rodu hyping on his site: http://rodutobaccotruth.blogspot.com/2015/11/youth-e-cigarette-bans-incr...
ACSH:  http://acsh.org/2015/10/electronic-cigarette-access-and-adolescent-smoking/
R Street:  http://www.rstreet.org/op-ed/study-e-cig-bans-on-minors-lead-to-higher-s...
 
Lauren Dutra helped me prepare this posting.

Comments

Comment: 

I was troubled by this study, even though I think it is quite possible that youth experimentation and initiation into e-cigarette use could be reducing or delaying youth initiation into smoking (and that it also quite possible that e-cigarettes and their marketing are prompting initiation among youth who would otherwise never regularly use nicotine or tobacco).  Your list serve posting mentioned some of the reasons I was concerned.  Here are some others:
 
<ul;
<li;The study’s analysis of its findings and related conclusions assume that a new state law prohibiting e-cigarette sales to youth reduces youth access to e-cigarettes.&nbsp; It is clear from related research, however, that the level of enforcement of any such new youth access law would be critically important as to whether it had any actual impact on youth access or how strong or weak its impact might be.&nbsp; Yet the study did not look at state enforcement budgets or efforts at all.</li;
</ul;
&nbsp;
<ul;
<li;Because of the new stores selling e-cigs, that don’t sell cigarettes, any significant enforcement of the new state laws prohibiting e-cig sales to youth that were done could shift inspections and &nbsp;enforcement away from stores that sell cigarettes and other tobacco products, which could have some upward impact on youth smoking levels.&nbsp; Whether that might be a factor behind the trends the study found was not considered.</li;
</ul;
&nbsp;
<ul;
<li;The study implicitly assumes uniform e-cigarette pricing, marketing and availability and related trends nationwide.&nbsp; But if e-cigarette availability to youth does impact youth smoking rates, as the study concludes, the different youth smoking trends in different states could be explained, at least in part, by different levels of -cigarette pricing, marketing and availability in different states (e.g., early marketing could have focused on urban areas or urban states). But the study did not consider that.</li;
</ul;
&nbsp;
<ul;
<li;There must be some e-cigarette youth use data for some of the states the study looked at to see if youth e-cig trends in states with and without laws prohibiting sales to youth appear to be consistent with the study’s findings or not.</li;
</ul;
&nbsp;
Also, there is a serious ethical issue that needs more attention in regard to allowing, or promoting, e-cigarette use by youth to reduce youth smoking (which the study appears to endorse through its proposal to have a lower minimum age for e-cig use than for cigarettes), especially if pushing e-cigarettes to keep kids away from smoking also initiates youth who would otherwise use no nicotine or tobacco products into addicted e-cig use and/or addicted smoking.&nbsp; There are also similar ethical issues raised by pushing e-cigarette use as a smoking substitute among existing smokers if doing so promotes relapse into addicted e-cig use or worse among smokers who would otherwise stay totally quit or delays or prevents cessation from any and all smoking or nicotine use among current smokers.&nbsp; Does the goal of producing net public health gains trump causing new, serious harms to youth and others who otherwise would not be harmed?&nbsp; I’m not sure what the answer to that is (and the answer might depend on specific circumstances and trade offs); but I think the question deserves a lot more consideration by more public health folks.

Comment: 

I largely concur with assessment of Friedman paper. I have many concerns with employed approach and manner in which data are being misinterpreted.
&nbsp;
As noted, major limitation of the study is that it did not directly measure youth access to electronic cigarettes or actual e-cigarette use. As such, it’s not really possible to determine whether the study actually measured reduced access to and use of e-cigarettes, or whether the finding is the result of some other factor that is related to youth smoking and the characteristics of states that have implemented youth access laws. The analytical sample also starts from 2002 when e-cigarettes had not been introduced to the U.S. market. I would suspect that the results of this analysis could be contaminated by misclassification of data from early years. With three waves of data (e.g. 2008-2009, 2010-2011, 2012-2013), the effect of state bans would likely not be substantial in magnitude, nor statistically significant. Additionally, a significant fraction of the e-cigarette youth access laws were toothless – i.e. sponsored by the tobacco industry and/or contained little or no enforcement or penalties. Moreover, there is little data that suggests that even more aggressive youth access bans on cigarettes have had a significant rapid impact (in either direction) on cigarette sales. Thus, such an e-cigarette youth access law seems quite unlikely to have influenced youth experimentation/use in that magnitude by itself.
&nbsp;

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