Friday 30 April 2021

Conclusions from the EU's scientists and others on whether e-cigarettes help smokers quit

This week the European Union's scientific advisers issued their "Final Opinion on Electronic Cigarettes". This report strengthens concerns about the risks associated with e-cigarette use, while failing to find more than weak evidence that they help smokers quit. 

This post summarizes the findings of this report, and provides a summary of scientific reports published subsequent to the release of the SCHEER's draft opinion last fall.

The EU scientific reaffirms its conclusions on the risks of e-cigarettes

More than two years have passed since the EU's Scientific Committee on Health, Enviornmental and Emerging Risks (SCHEER) was first handed the mandate of assesssing the risks and benefits of e-cigarettes in February 2019. This report is intended to assist the European Union in its upcoming review of its Tobacco Products Directive (now 7 years old). In its assessment, the committee relied on evidence "mainly from review articles published between January 2015 and April 2019 as well as relevant primary sources and literature beyond this period." 

Last September the committee issued its preliminary opinion, following which a consultation paper allowed public comment on their conclusions. Over the past months the SCHEER's working group on e-cigarettes has been reviewing the comments of e-cigarette manufacturers like British American Tobacco and others. (A separate report on that consultation is forthcoming). This week the SCHEER signed off on the final opinion, offering its scientific advice that the:
  • evidence supporting e-cigarettes as an effective smoking cessation device was "weak". 
  • evidence that second-hand exposure to e-cigarette vapour posed risks was "weak to moderate".
  • evidence that e-cigarettes helped smokers cut down on the amount smoked was "weak to moderate".
  • evidence that e-cigarettes could cause cancer in the respiratory tract was "weak to moderate".
  • evidence that e-cigarettes posed risks for coronary disease was "moderate".
  • evidence that e-cigarettes were a gateway to smoking for young people was "moderate"
  • evidence that e-cigarettes with nicotine were addictive was "strong"
  • evidence that flavours in these products contribute to initiation was "strong".

In its revisions to the opinion, the SCHEER clarified that it was cautioning against the use of e-cigarettes as as cessation products outside a clinical intervention: "There is a lack of robust longitudinal data on the effect of electronic cigarettes on smoking cessation. Until such research is available, electronic cigarettes should only be considered to support smoking cessation for a limited time and under supervision." This statement is aligned with the conclusions of other government-mandated reviews(described below).

More studies supporting a cautionary approach

Subsequent to the release of the SCHEER's draft opinion last fall, a number of papers have been released which cast doubt on the usefulness of encouraging the use of e-cigarettes as cessation aids  when purchased as consumer products outside a therapeutic intervention.  

A December 2020 study by Richard Wang and associates  examined e-cigarettes as smoking cessation aids using meta-analyses.[1] The meta-analyses included all pertinent studies published up to January 2020. The meta-analyses performed included 55 observational studies and 9 randomized control trials (RCTs). The study concludes that, overall, e-cigarettes, as consumer products, are not associated with increased smoking cessation in the adult population. In observational studies, whether smokers showed no motivation or some motivation to quit smoking, e-cigarettes were not effective in achieving smoking cessation. Smokers who used e-cigarettes less than daily were less likely to quit smoking. If smokers also used e-cigarettes daily, they were more likely to quit smoking. In randomized control trials, provision of free e-cigarettes as a therapeutic intervention was associated with increased smoking cessation. This study adds to the increasing evidence that e-cigarettes used as consumer products are not effective as smoking cessation devices, while e-cigarettes given therapeutically in controlled clinical settings may help some people quit smoking.

Another similar meta-analysis published in January 2021 found similar results. [2] Zhang and colleagues included fewer studies in their meta-analyses (35), but had similar findings. Intensive use of e-cigarettes and use in randomized control trials in clinical settings were associated with small increases in smoking cessation, described by the authors as having "low certainty." They did not assess persistent use of e-cigarettes among successful quitters. A secondary finding was that adolescent e-cigarette users were three times more likely to become cigarette smokers, consistent with other research.[3,4]

Similar results were reported by McDermott and colleagues and published in March 2021. [5] They analyzed data from a longitudinal survey conducted in the United Kingdom from 2012 to 2017. Daily e-cigarette users were significantly more likely to quit smoking, while non-daily e-cigarette users were significantly less likely to quit smoking. Non-daily use was the more frequent pattern. Non-daily users accounted for 60% of all e-cigarette users.

In October 2020, we reported on studies of the same relationship of e-cigarette use for smoking cessation.[6] Using very different methods - analysis of longitudinal data form the US PATH study - two groups of researchers reached very much the same conclusion as Richard Wang and his colleagues - that e-cigarettes, when used as consumer products are not effective as smoking cessation devices.

Since then another study that used PATH data has been published, concluded that there was some benefit for smoking cessation from e-cigarettes.[7] However, this study's conclusions have been challenged on the basis of methodological flaws in the analysis, which John Pierce and colleagues [8] have described in detail.

Converging conclusions by scientific authorities

Research findings about e-cigarettes, sold as consumer products and used as smoking cessation aids, are converging. Overall, e-cigarettes sold as consumer products are not effective as smoking cessation devices, although benefits were found when they are included as part of a clinical intervention.

In October 2020 a Cochrane Review of randomized control trials of e-cigarettes for smoking cessation was published, and updated in April 2021 [9]. It included a meta-analysis that produced results similar to those produced by Wang et al.'s meta-analysis of 9 RCTs, showing that e-cigarettes have some benefit, similar to other smoking cessation methods, when used in a controlled clinical setting. However, unlike the PATH analyses and the study by Wang et al., the Cochrane review did not provide any information on how e-cigarettes might be used or misused when sold as consumer products. This Cochrane Review has been criticized because it stops short of providing information on what might happen when e-cigarettes are used as consumer products. It has also been criticized because several of the authors were also authors of the studies under review. In addition the RCTs under review were criticized for being are outside the scope of what is considered appropriate use of RCT methodology. Criticisms have been published by researchers in California [10] and Australia.[11]

In January 2021, the United States Preventive Services Task Force recommended against counselling smokers to use e-cigarettes. "The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of e-cigarettes for tobacco cessation in adults, including pregnant persons. The USPSTF recommends that clinicians direct patients who use tobacco to other tobacco cessation interventions with proven effectiveness and established safety." [12]

In June 2020 the Irish Health Research Board [13] reported that "e-cigarettes were not more effective for smoking cessation than approved nicotine replacement therapies (NRTs), which questions the need for e-cigarettes as a smoking cessation intervention. In the second review, we found that e-cigarettes were associated with initiation of conventional cigarette smoking among adolescents, which identifies a potentially serious harm."

A report by Spain's public health agency [14] concluded in 2020 that "To date, no toxicological or drug studies have been performed on the long-term safety of e-cigarette use in humans; without these data it is impossible to say with certainty that e-cigarettes are safer than cigarettes. With this in mind it is impossible to recommend these devices as a useful tool against the cessation of traditional tobacco consumption." (machine translation)

Reviews on the impact of e-cigarettes on tobacco use conducted for the government of Australia by that country's National Centre for Epidemiology and Public Health [15] concluded that e-cigarettes did not help people quit smoking, but did increase the probability of a young person starting to smoke. 

For the Netherlands government, the Trimbos Institute reviewed the literature [16] and found that e-cigarettes were effective as cessation products for only a small group of smokers, and that success rates were comparable to "regular" methods. Because most e-cigarette users in that country also continued to smoke, it cautioned about the additional risks of dual use. 

Take away

The studies to date, whether longitudinal data analysis, randomized control trials or meta-analysis of e-cigarettes as consumer products, when dual use was assessed, all found high levels of dual use, known to be hazardous, and high prevalence of continuing use of e-cigarettes, even if smokers were successfully able to use them to quit smoking.

Smokers who use e-cigarettes daily are more likely than not to find e-cigarettes helpful in quitting smoking. However, this comes at the cost of likely continuing addiction to e-cigarettes. Among less frequent users of e-cigarettes, e-cigarette use makes smoking cessation less likely.
Daily e-cigarettes increase the likelihood of smoking cessation , but decreases cessation for less-than-daily users of e-cigarettes. Overall, e-cigarettes, when used as consumer products, do not increase smoking cessation rates.

E-cigarettes can be helpful as smoking cessation aids, but only in clinical settings. They are about as effective as other methods, but, unlike other therapeutic methods, they do not pass a test of safety for widespread use. There is a high risk of dual use, a high risk of continuing use, and a high risk of uptake of e-cigarettes by never smokers. Since they are only about as effective as other methods and cannot meet safety tests, it is highly questionable why sales of e-cigarettes as fast moving consumer goods (including to never smokers) should continue to be allowed in preference to imposing the types of restrictions required of other therapeutic products. 


References

[1] Richard J. Wang, Sudhamayi Bhadriraju, and Stanton A. Glantz:E-Cigarette Use and Adult Cigarette Smoking Cessation: A Meta-Analysis. American Journal of Public Health, https://doi.org/10.2105/AJPH.2020.305999

[2] Ying-Ying Zhang, Fan-Long Bu1, Fei Dong, Jian-Hua Wang, Si-Jia Zhu, Xiao-Wen Zhang, Nicola Robinson, Jian-Ping Liu. The effect of e-cigarettes on smoking cessation and cigarettesmoking initiation: An evidence-based rapid review and meta-analysis. Tob. Induc. Dis. 2021;19(January):4 https://doi.org/10.18332/tid/131624.

[3] Physicians for a Smoke-Free Canada. An update on evidence linking teen vaping to cigarette smoking. 15 November 2020. http://smoke-free-canada.blogspot.com/2020/11/an-update-on-evidence-linking-teen_15.html.

[4] John P. Pierce, Ruifeng Chen, Eric C. Leas, Martha M. White, Sheila Kealey, Matthew D. Stone, Tarik Benmarhnia, Dennis R. Trinidad, David R. Strong and Karen Messer. Use of E-cigarettes and Other Tobacco Products and Progression to Daily Cigarette Smoking. Pediatrics January 2021, e2020025122; DOI: https://doi.org/10.1542/peds.2020-025122.

[5] Máirtín S. McDermott, Katherine A. East, Leonie S. Brose, Ann McNeill, Timea R. Partos.The effectiveness of using e‐cigarettes for quitting smoking compared to other cessation methods among adults in the United Kingdom. Addiction. 09 March 2021. https://doi.org/10.1111/add.15474

[6] Physicians for a Smoke-Free Canada. New longitudinal studies find little support for e-cigarettes as an effective tool for population-level smoking cessation. 15 October 2020. http://smoke-free-canada.blogspot.com/2020/10/new-longitudinal-studies-find-little.html.

[7] Allison M. Glasser MPH, Mahathi Vojjala, Jennifer Cantrell, David T. Levy, Daniel P. Giovenco, David Abrams, Raymond Niaura. Patterns of E-cigarette Use and Subsequent Cigarette Smoking Cessation Over 2 Years (2013/2014–2015/2016) in the Population Assessment of Tobacco and Health Study. Nicotine & Tobacco Research, 2020, 1–9. 17 September 2020. doi:10.1093/ntr/ntaa182.

[8] John P. Pierce, Eric C. Leas, Tarik Benmarhnia, Sara B. McMenamin, David R. Strong, Ruifeng Chen, Karen Messer. E-cigarettes and Cessation: The Introduction of Substantial Bias in Analyses of PATH Study.14 November 2020. Nicotine & Tobacco Research, 2020, 1–2 doi:10.1093/ntr/ntaa234.

[9] Jamie Hartmann-Boyce, Hayden McRobbie, Nicola Lindson, Chris Bullen, Rachna Begh, Annika Theodoulou, Caitlin Notley, Nancy A Rigotti, Tari Turner, Ailsa R Butler, Thomas R Fanshawe, Peter Hajek. Electronic cigarettes for smoking cessation. Cochrane Database of Systematic Reviews. 14 October 2020 https://www.cochranelibrary.com/.





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