Myth: Alternative nicotine products are a gateway to smoking

The Gateway Hypothesis

Papers

2024: The “Gateway” hypothesis: evaluation of evidence and alternative explanations

• Conclusion: "Evidence offered in support of the gateway hypothesis does not establish that ENDS use causes youth to also smoke cigarettes. Instead, this evidence is better interpreted as resulting from a common liability to use both ENDS and cigarettes. Population-level trends are inconsistent with the gateway hypothesis, and instead are consistent with (but do not prove) ENDS displacing cigarettes. Policies based on misinterpreting a causal gateway effect may be ineffective at best, and risk the negative unintended consequence of increased cigarette smoking."
  • Citation: Selya, A. The “Gateway” hypothesis: evaluation of evidence and alternative explanations. Harm Reduct J 21, 113 (2024). https://doi.org/10.1186/s12954-024-01034-6
    • Acknowledgment: The author thanks Joe Gitchell, Sooyong Kim, and Saul Shiffman, all of Pinney Associates, Inc. for their feedback on an early draft of this manuscript, and Floe Foxon and Sooyong Kim for assistance with manuscript formatting. Through Pinney Associates, Inc., AS provides consulting services on tobacco harm reduction to Juul Labs, Inc. (JLI). JLI partially supported the preparation of this manuscript, and reviewed and commented on a near-final version. After the initial submission of this manuscript, AS also began individually providing consulting services on behavioral science to the Center of Excellence for the Acceleration of Harm Reduction (CoEHAR) through ECLAT Srl, which received funding from the Foundation for a Smoke-Free World (FSFW). Neither CoEHAR nor FSFW had any role in, or oversight of, this commentary.

Articles/Blogs/Op-Eds

2016: How not to be duped by gateway effect claims

• "Sometimes studies appear that can create the appearance of the discovery of a ‘gateway effect’ – the idea that vaping causes young people to progress to smoking...Here is an eight-point guide to evaluating such studies and the politically motivated claims that often go with them."

Vaping Up < - > Smoking Down

Papers

2024: Increased e-cigarette use prevalence is associated with decreased smoking prevalence among US adults

• Nationally representative population-level data on tobacco product use by US adults continue to support the existence of an association between increasing prevalence of e-cigarette use and decreasing prevalence of cigarette smoking, i.e., possible substitution between cigarettes and e-cigarettes.
  • Citation: Foxon F, Selya A, Gitchell J, Shiffman S. Increased e-cigarette use prevalence is associated with decreased smoking prevalence among US adults. Harm Reduct J. 2024 Jul 18;21(1):136. doi: 10.1186/s12954-024-01056-0. PMID: 39026245; PMCID: PMC11256395.
    • Acknowledgment: Through PinneyAssociates, FF, AS, JG, and SS provide consulting services on tobacco harm reduction on an exclusive basis to Juul Labs Inc. The preparation of the previously-published version of this manuscript was funded by JLI, who reviewed and provided comments on a draft manuscript of the previously-published version. The present, updated version did not receive any funding or review from JLI, and was self-funded by PinneyAssociates. The content and the decision to publish are the responsibility of the authors. JG and SS also own interest in a novel nicotine gum that has neither been developed nor commercialized.

2022: Association of quarterly prevalence of e-cigarette use with ever regular smoking among young adults in England: a time–series analysis between 2007 and 2018

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2021: High School Seniors Who Used E-Cigarettes May Have Otherwise Been Cigarette Smokers: Evidence From Monitoring the Future (United States, 2009–2018)

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2021: Association of genetic liability to smoking initiation with e-cigarette use in young adults: A cohort study

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2021: Trends in electronic cigarette use and conventional smoking: quantifying a possible 'diversion' effect among US adolescents

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2021: Association of initial e-cigarette and other tobacco product use with subsequent cigarette smoking in adolescents: a cross-sectional, matched control study

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2021: Testimony in Netherlands pertaining to a potential flavour / flavor ban: Regulation of e-cigarette flavours – a response

• Signed by 24 experts from around the world
• Covers 12 key points, including the theory of a gateway effect

2020: Association of initial e-cigarette and other tobacco product use with subsequent cigarette smoking in adolescents: a cross-sectional, matched control study

• Conclusion: In conclusion, this matched control analysis of NYTS data from 2014 to 2017 suggests that for adolescents initiation with e-cigarettes is associated with a reduced risk of subsequent cigarette smoking compared with initiators with other combustible and non-combustible tobacco products use, and propensity score matched adolescents without initial e-cigarette use. This suggests that, over the time period considered, e-cigarettes were unlikely to have acted as an important gateway towards cigarette smoking and may, in fact, have acted as a gateway away from smoking for vulnerable adolescents; this is consistent with the decrease in youth cigarette smoking prevalence over the same time period that youth e-cigarette use increased between 2014 and 2017.
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2020: Trends in Tobacco Use Among Adolescents by Grade, Sex, and Race, 1991-2019

• This cross-sectional study suggests that, despite the increase in the prevalence of e-cigarette use among adolescents between 2011 and 2019, the prevalence of cigarette and smokeless tobacco use has decreased more rapidly during the same period compared with earlier years.
• Link to PDF on study page
  • Citation: Meza R, Jimenez-Mendoza E, Levy DT. Trends in Tobacco Use Among Adolescents by Grade, Sex, and Race, 1991-2019. JAMA Netw Open. 2020;3(12):e2027465. doi:10.1001/jamanetworkopen.2020.27465
    • Acknowledgement: Research reported in this publication was supported by award U54CA229974 from the National Cancer Institute of the National Institutes of Health and the US Food and Drug Administration Center for Tobacco Products.

2020: Electronic cigarettes, nicotine use trends and use initiation ages among US adolescents from 1999 to 2018

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2020: Does e-cigarette experimentation increase the transition to daily smoking among young ever-smokers in France?

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2019: Examining the relationship of vaping to smoking initiation among US youth and young adults: a reality check

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2019: The Relationship Between Electronic Cigarette Use and Conventional Cigarette Smoking Is Largely Attributable to Shared Risk Factors

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2019 The Impact of Electronic Cigarettes on Cigarette Smoking By Americans and Its Health and Economic Implications

• In this study, we examined the growing use of electronic cigarettes and its implications. The wide use of e-cigarettes is a very recent development, and issues regarding their long-term effects and significance cannot be fully analyzed at this time. Using CDC and other data covering the last decade, however, we examined the relationship between the recent sharp increase in e-cigarette use among Americans and the contemporaneous acceleration in the declining rate of cigarette smoking. We found that the sharp increase in e-cigarette use across many groups can explain as much as 70 percent of the accelerating decline in smoking rates. We also found no reasonable evidential basis for concerns that e-cigarettes are a gateway to cigarette smoking. We further found that e-cigarettes are highly effective in helping people stop smoking cigarettes.
• Finally, we analyzed the impact of the sharp increase in e-cigarette use and the accelerating decline in cigarette smoking on healthcare costs and economic productivity. We found that while e-cigarette users incur lower healthcare costs than cigarette smokers or ex-smokers, the longer lifespans of e-cigarette users and ex-smokers who used e-cigarettes to quit smoking result in higher lifetime healthcare costs. However, we also found that the value of the additional years of life associated with using e-cigarettes instead of smoking is much greater than the additional healthcare costs. Lastly, we found that the increase in e-cigarette use and the associated reduction in smoking rates results in large productivity benefits, mainly from lower rates of illness.
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2015: The Impact of Flavor Descriptors on Nonsmoking Teens’ and Adult Smokers’ Interest in Electronic Cigarettes

• Nonsmoking teens’ interest in e-cigarettes was very low.
• Adult smokers’ interest was significantly higher overall and for each flavor.
• Teen interest did not vary by flavor, but adult interest did.
• Past-30-day adult e-cigarette users had the greatest interest in e-cigarettes, and their interest was most affected by flavor.
• Nonsmoking teens who had never tried e-cigarettes had the lowest interest in flavors, followed by adults who had never tried e-cigarettes
• PDF Version
  • Citation: Saul Shiffman, PhD, Mark A Sembower, MS, Janine L Pillitteri, PhD, Karen K Gerlach, PhD, MPH, Joseph G Gitchell, BA, The Impact of Flavor Descriptors on Nonsmoking Teens’ and Adult Smokers’ Interest in Electronic Cigarettes, Nicotine & Tobacco Research, Volume 17, Issue 10, October 2015, Pages 1255–1262, doi: 10.1093/ntr/ntu333
    • Acknowledgement: This work was supported by NJOY, a company that markets electronic cigarettes, but does not make or sell any combustible tobacco products. All authors work for Pinney Associates and provide consulting services to GlaxoSmithKline Consumer Healthcare on their stop-smoking medications and to NJOY, Inc. on electronic nicotine delivery systems (ENDS). SS and JGG also own an interest in a novel nicotine medication in development. The study sponsor was involved in discussion of the study design, but had no role in study execution, data collection, data analysis, or writing of the manuscript, nor did the sponsor review the manuscript prior to submission.

Critiques of Papers Claiming Gateway

2024: Comments RE: Association between e-cigarette use and susceptibility to tobacco product use: findings from the 2019 China National Youth Tobacco Survey

• "Causation vs. association. While the authors are careful in most places to avoid claiming that this association is causal, the authors seem to ultimately conclude in favor of a (causal) gateway hypothesis, which is inappropriate given unmeasured confounding by other “common liability” factors, and the cross-sectional nature of the data." (Selya)
• Referring to: Li S, Zeng X, Di X, Liu S. Association between e-cigarette use and susceptibility to tobacco product use: findings from the 2019 China National Youth Tobacco Survey. Front Public Health. 2024 Jan 15;11:1272680. PMID: 38288432; PMCID: PMC10823011 doi: 10.3389/fpubh.2023.1272680

2022: Comments RE: Impact of the e-cigarette era on cigarette smoking among youth in the United States: A population-level study

• "The present re-analysis shows that the report of a gateway effect in the NYTS data by Harrell et al. is not supported by these data when appropriate statistical methodology is applied." (Foxon)
• Referring to: Harrell MB, Mantey DS, Chen B, Kelder SH, Barrington-Trimis J. Impact of the e-cigarette era on cigarette smoking among youth in the United States: A population-level study. Prev Med. 2022 Nov;164:107265. Epub 2022 Sep 22. PMID: 36152819; PMCID: PMC10381788. doi: 10.1016/j.ypmed.2022.107265