E-cigarettes can help to quit smoking, but are used more often and for longer than nicotine replacement products
A randomized study published in NEJM  showed that use of e-cigarettes as smoking cessation treatment was more effective than nicotine replacement (NR) therapy. The 1-year abstinence rate (validated biochemically) was 18.0% in those assigned to e-cigarettes and 9.9% in the NR group (RR: 1.83, 95%CI: 1.30-2.58).
In this study, 886 middle-aged clients of National Health Services (NHS) Stop Smoking Services were randomized to e-cigarettes or an NR-product (or combination of products) of their choice. Supplies of NR products for up to 3 months or an e-cigarette starter kit were provided. Both strategies were accompanied by behavioral support, which involved weekly one-on-one sessions with a clinician for at least 4 weeks after the quit date. During these sessions, expired carbon monoxide levels were measured. Participants were asked about product use at 26 weeks and 52 weeks, and asked back for a carbon monoxide reading if they reported abstinence at 52 weeks.
In those still abstaining from smoking at 52 weeks, individuals in the e-cigarette group more often still used the assigned product than those in the NR group (63/79: 80% vs. 4/44: 9%).
In those with sustained abstinence at 4 weeks, but not at the end of study, relapse rate and time to relapse did not differ between groups. Overall adherence to products was similar in both groups. While e-cigarettes and NR products were all perceived as less satisfying than cigarettes, e-cigarettes provided greater satisfaction and were considered more helpful to refrain from smoking than NR products. Thus, even though NR was used under expert guidance and with access to the full range of products, or a combination thereof, e-cigarettes were more effective for smoking cessation.
Health consequences of e-cigarette use uncertain
It is important to note that e-cigarettes were used more often and for a longer time than NR products. In an accompanying editorial, Borrelli and O’Connor  emphasize this finding in relation to concerns about health consequences of long-term e-cigarette use. Various lines of evidence have suggested potential adverse biological effects of the toxins in e-cigarette vapor. Thus, the transition from tobacco smoking to indefinite e-cigarette use should maybe not be considered as a completely successful smoking-cessation outcome, they argue. The societal impact of adult e-cigarette on children and young adults should also be considered, both in light of exposing them to e-cigarette vapor and of setting an example of addictive behavior.
The U.S Food and Drug Administration (FDA) have not approved e-cigarettes for smoking cessation. While e-cigarettes are considered safer than traditional combustible cigarettes, it remains controversial whether e-cigarettes should be recommended as first-line treatment to assist smoking cessation. Borrelli and O’Connor suggest that e-cigarettes be used only when FDA-approved treatment (combined with behavioral counseling) fail, and that patients be advised to use the lowest does needed to manage their cravings. A clear timeline and ‘off ramp’ for use should be established. Like other pharmacologic smoking-cessation treatments, use of e-cigarettes should be monitored by health care providers.
Negative consequences of flavoring
In another editorial, Drazen et al.  focus on the addictive properties of nicotine. To make the initial exposure to this non-natural behavior more pleasurable, flavors are added to the liquid from which the nicotine aerosol is generated. This appears to work, especially in adolescent. The rates of vaping among teenagers are increasing rapidly. Nicotine-addicted adolescents may switch to use of combustible tobacco at a later stage, or even other substances. Therefore, Drazen et al. suggest that the sale of flavored nicotine products for use in e-cigarettes should be banned altogether. The function of e-cigarettes in helping people quit smoking is adequately addressed by liquids that are not flavored.
Increased risk of CV endpoints in e-cigarette users
No long-term data on the health consequences of using e-cigarettes are available. Recent data, however, presented at the international Stroke Conference and reported at Healio.com , point in the direction of e-cigarette use being associated with an increased risk for stroke, myocardial infarction and angina or coronary heart disease. Odds ratio’s in the range of 1.4 to 1.7 were seen for these endpoints, when comparing almost 67.000 e-cigarette users with almost 345.000 never-users from the 2016 Behavioral Risk Factor Surveillance System, of the University of Kansas School of Medicine. This was an observational study and thus no causal link can be demonstrated. The findings do justify long-term studies to explore the relationship more carefully.