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Electronic cigarettes (e-cigarettes) contain refined nicotine dissolved in propylene glycol, glycerine or other humectants, which is vaporised with a battery-powered heating element, activated by suction or manually, and delivered into the airways.1 E-cigarettes have been shown to reduce craving and withdrawal symptoms in abstinent smokers and, as nicotine is delivered without tobacco combustion, are thought to be substantially safer than cigarettes.2 While e-cigarette use is rapidly increasing, relatively little is known about their efficacy for smoking cessation, particularly compared with established nicotine-containing pharmacological aids.3
A randomised controlled trial to assess the effectiveness of e-cigarettes was carried out in New Zealand. Adult participants were block-randomised (stratified by ethnicity, dependence and sex) to one of three conditions in a 4:4:1 ratio: elusion nicotine e-cigarettes (N=289), nicotine patch (N=295) or nicotine-free e-cigarettes (N=73). E-cigarettes or vouchers to obtain patches from pharmacies were sent to participants. All groups were instructed to use products from 1 week before until 12 weeks following their quit date and were referred to telephone-based behavioural support. The primary outcome measure was 6 months continuous abstinence, verified by exhaled carbon monoxide measurement (<10 ppm). Other outcome measures included 7-day point prevalence, cigarette consumption, product usage and adverse events. Results were presented as relative risks (RR) with 95% CI.
Intention-to-treat analysis failed to find significant differences between e-cigarette and patch or nicotine-free e-cigarette groups. Among e-cigarette users 7.3% (N=21) were abstinent at 6 months, compared with 5.8% (N=17) of patch users (RR=1.26, 95% CI 0.68 to 2.34) and 4.1% (N=3) of nicotine-free e-cigarette users (RR=1.77, 95% CI 0.54 to 5.77). There were also no differences in point-prevalence abstinence at 6 months or complete case analysis. However, repeated measures analysis based on self-report suggested a marginally higher overall effect of nicotine e-cigarettes over patches (RR=1.61, 95% CI 1.00 to 2.57), while median time to relapse was twice as long in the nicotine e-cigarette group. Cigarette consumption decreased significantly more among relapsers in the nicotine e-cigarette group compared with the nicotine patch group and more participants in the nicotine and nicotine-free e-cigarette groups continued to use the product (29% and 35% at 6 months, respectively) than in the nicotine patch group (8%). No significant differences in serious adverse events were detected.
Given the meteoric rise of e-cigarettes and paucity of related research, this study provides much-needed data to inform the choices of policy makers and consumers, finding that e-cigarettes are safe and reasonably effective smoking cessation aids. However, as the authors acknowledge, the study was underpowered to conclude superiority of e-cigarettes over nicotine patches. What's more, only one e-cigarette brand with relatively poor nicotine delivery was tested. Already, there are new e-cigarette models that deliver nicotine faster and in greater doses which are likely to be more effective.1
The interpretation of findings is further complicated by differences in demand characteristics imposed by the design (posted e-cigarettes vs patches collected from pharmacies) and in the product types compared (topical nicotine administration with e-cigarette vs systemic administration with patches). Moreover, only minimal behavioural support was provided to increase ecological validity, which may have added more unnecessary noise, as awareness and ease of use will have been greater for patches compared with e-cigarettes. Ultimately, given the fast-moving nature of the e-cigarette market and changing user characteristics, experimental studies, even if pragmatic in design, can only ever provide a delayed snapshot view of the real-world effectiveness of e-cigarettes, and epidemiological data are needed to evaluate their impact.
Interestingly, a substantial proportion of participants in this study engaged in harm reduction, becoming long-term e-cigarette users and reducing their conventional cigarette consumption. Thus, against the backdrop of ongoing debates on tighter regulation of e-cigarettes,4 ,5 a sole focus on smoking cessation may be misguided. From a public health perspective, the permanent switch from combustible to non-combustible products is an important endpoint in itself. Nonetheless, the finding that e-cigarettes are at least as effective as existing licensed, nicotine-containing smoking cessation products should go some way towards easing, if not completely allaying, the fears of many health professionals observing their fast uptake among smokers.6
Competing interests LS has received honoraria for talk and travel expenses from manufacturers of medications for smoking cessation to attend meetings and workshops. MG received a research grant from Pfizer, manufacturer of smoking cessation medications. Neither author has links with the tobacco or e-cigarette industry.
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