Efficacy of E-Cigarettes for Smoking Cessation

Electronic nicotine delivery systems (ENDS) are battery-operated devices that heat and aerosolize a liquid solution, which is inhaled by the user. ENDS may be important for reducing harm among people who smoke cigarettes, since ENDS emit fewer toxicants per puff compared with cigarettes.¹ Thus, there is a significant interest in understanding whether ENDS promote smoking cessation.

The study by Auer and colleagues was a multisite randomized controlled trial conducted in Switzerland. A total of 1246 participants who smoked cigarettes were randomized to receive either ENDS plus standard smoking cessation treatment (SCT; which included behavioral counseling and the option of nicotine-replacement therapy) or SCT alone. The key finding of the study was that ENDS plus SCT resulted in higher biochemically confirmed continuous abstinence from cigarette smoking at 6 months compared with SCT alone (28.9% vs 16.3%; RR 1.77; 95% CI, 1.43–2.20). There were more minor adverse events in the ENDS plus SCT group, although serious adverse events were similar between the two groups. There was a higher rate of self-reported complete nicotine abstinence (ie, no cigarettes, e-cigarettes, nicotine-replacement therapy) in the control group versus the ENDS group (33.7% vs 20.1%).

The study is an important addition to the field, as it provides additional evidence that ENDS are effective for smoking cessation. An earlier trial conducted in the UK found that ENDS were more effective for smoking cessation compared with conventional nicotine-replacement therapy.² The observed results are likely due to the fact that ENDS, like cigarettes, can deliver nicotine rapidly and in large amounts to the brain.³ Cigarette smoking rates in the US have declined over the past decade, likely, at least in part, due to increased availability and use of ENDS. Important questions remain, including how best to implement ENDS for smoking cessation in clinical settings and whether ENDS definitively reduce smoking-related harm.

References

1. Goniewicz ML, Knysak J, Gawron M, et al. Levels of selected carcinogens and toxicants in vapour from electronic cigarettes. Tob Control. 2014;23(2):133-139. https://tobaccocontrol.bmj.com/content/23/2/133
2. McRobbie H, Bullen C, Hartmann-Boyce J, et al. Electronic cigarettes for smoking cessation and reduction. Cochrane Database Syst Rev. 2014;12:Cd010216. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010216.pub2/full
3. Baldassarri SR, Hillmer AT, Anderson JM, et al. Use of electronic cigarettes leads to significant beta2-nicotinic acetylcholine receptor occupancy: evidence from a PET imaging study. Nicotine Tob Res. 2018;20(4):425-433. https://academic.oup.com/ntr/article-abstract/20/4/425/3766293?redirectedFrom=fulltext&login=false

Cigarette smoking remains a major cause of premature cardiovascular disease (CVD) and death. Stopping smoking before the age of 40 avoids most of the diseases associated with smoking, and, in people who smoke and have CVD, the risk drops quickly after quitting smoking. Unfortunately, quitting smoking is difficult for many, even when treated with counseling and approved smoking-cessation medications. Most of the harm from smoking is caused by combustion products of burning tobacco, related to extremely high levels of oxidative stress. Electronic cigarettes provide nicotine by inhalation, resulting in nicotine effects similar to those of smoking but with much lower levels of oxidant chemical exposure. E-cigarettes have been shown to aid smoking cessation in several clinical trials, but the safety of long term e-cigarette use for adults and concerns about use in youth make many physicians hesitant to support their use.

The present study is the largest randomized trial of e-cigarettes for smoking cessation to date, conducted in five ambulatory healthcare settings in Switzerland. Overall, 1246 smokers were randomized to receive free e-cigarettes and liquids for 6 months or to a control group, both of which received smoking-cessation counseling. The rate of biochemically confirmed continuous abstinence from smoking from quit date to 6 months was 28.9% in the e-cigarette group and 16.3% in the control group (RR, 1.77; 95% CI, 1.43–2.20). The self-reported rate of 7-day abstinence at 6 months was 53.4% in the e-cigarette group and 32.1% in the control group (RR, 1.67; 95% CI, 1.45–1.91). Most of the participants who quit smoking by using e-cigarettes continued to use e-cigarettes at 6 months, similar to what has been observed in other trials. The rate of serious adverse events was similar in the e-cigarette and control groups. Smokers who switched to e-cigarettes reported significantly fewer respiratory symptoms than smokers in the control group.

Cochrane reviews of published clinical trials have confirmed that e-cigarettes are more effective than nicotine medication in promoting smoking cessation. Of concern to many physicians, however, is the potential risk of ongoing nicotine use, particularly in patients with CVD. Long-term data on the safety of e-cigarette use in patients with CVD who have quit smoking are not yet available. However, data from Sweden with long-term use of smokeless tobacco, which delivers nicotine in similar doses as does smoking, indicates that nicotine per se does not accelerate coronary heart disease; however, it may pose an increased risk of fatal myocardial infarction and stroke.

The take-home message is that smokers, particularly those with CVD, need to stop smoking as soon as possible. Initial treatment should be with nicotine replacement medications or varenicline and behavioral counseling. For smokers who fail these interventions and wish to use e-cigarettes, it is reasonable to support their use. Once patients with CVD are confident that they no longer have urges to smoke cigarettes, it is prudent to encourage the cessation of e-cigarette use as well.