Research in context
Evidence before this study
The Cochrane review of e-cigarettes for smoking cessation sought studies published between 2004 and January, 2016. Two trials (N=953) were identified that measured smoking abstinence rates after 6 months or more, and both tested ad libitum use of first-generation e-cigarettes. Combined data from the trials showed that using a nicotine e-cigarette significantly increased smoking abstinence at 6 months compared with using a nicotine-free e-cigarette, although absolute quit rates were low (9% vs 4%). No serious adverse events were reported. Confidence in the findings was low given the “small number of trials, low event rates and wide confidence intervals around the estimates”. We sought to identify e-cigarette trials that measured smoking abstinence rates at 6 months or more, published between Jan 1, 2016, and June 30, 2019. We searched MEDLINE, Embase, and PsycINFO using the same search terms as the Cochrane Review (e-cig$ OR electr$ cigar$ OR electronic nicotine OR [vape or vaper or vapers or vaping]) plus “Randomized Controlled Trial” (Publication Type). We identified 48 articles, of which two were trials. The first trial (N=54 US companies, 6006 employees and their spouses) tested the effectiveness of four smoking cessation interventions (involving cessation medications, nicotine e-cigarettes, and financial rewards) against usual care (behavioural support). The verified continuous smoking abstinence rate at 6 months in the usual care plus e-cigarette group was higher, but not significantly different, to that observed in the usual care plus cessation medication group (1·0% vs 0·5%) or usual care alone (1·0% vs 0·1%). The second trial, done within the UK national stop smoking services, tested the effectiveness of second-generation e-cigarettes plus moderate level face-to-face behavioural support for smoking cessation (N=886). Self-reported continuous smoking abstinence rates at 6 months were higher in the 18 mg nicotine e-cigarette group (35·4%) than in those allocated 3 months of nicotine replacement therapy (NRT) (25·1%).
Added value of this study
Our study adds to the scarce trial evidence base on e-cigarettes as a smoking cessation tool and, to our knowledge, is the first to investigate the effectiveness and safety of combining nicotine patches and second-generation e-cigarettes (with and without nicotine) on smoking abstinence. We did the trial in a country with strong tobacco control measures, where advertising is restricted, use of e-cigarettes is low, and there was a ban on the sale of nicotine e-cigarettes. The findings may therefore be generalisable to countries with similar policy backgrounds. For example, Canada, Costa Rica, Ecuador, Japan, and Mexico had similar advertising restrictions on e-cigarettes at the time of the study and Australia, Canada, Costa Rica, Jamaica, Japan, Malaysia, Mexico, and Switzerland prohibited the sale of nicotine e-cigarettes. The research questions addressed in our trial have informed tobacco control policy being developed by the New Zealand Ministry of Health.
Implications of all the available evidence
All five published trials on e-cigarettes for smoking cessation are pragmatic in design, suggesting that under real-world conditions, e-cigarettes (with and without nicotine) could help some people quit smoking but the tobacco control policy environment within which they are available might affect cessation rates. E-cigarettes should be offered as one of the many smoking cessation aids available to people wanting to quit, but do not appear to be a solution for all. People using e-cigarettes should be encouraged to fully switch away from tobacco to e-cigarettes, with the aim of eventually also stopping vaping (if possible) given the lack of any long-term safety data for these devices. Future e-cigarette trials should consider carefully which comparator intervention(s) to use given the high likelihood of differential loss to follow-up (or withdrawal) when only usual care or NRT is offered.