E-cigarettes may work as well as nicotine patches in reducing and quitting smoking, but evidence is limited

BMJ 2014; 349 doi: (Published 17 December 2014) Cite this as: BMJ 2014;349:g7722
  1. Nigel Hawkes
  1. 1London

The first Cochrane review of electronic (e) cigarettes has concluded that people who use them can stop or reduce their smoking and that the devices may be roughly equivalent in efficacy to nicotine patches. But the evidence base was very limited—two randomised controlled trials and 11 observational studies—so the size of the benefit is uncertain.

The results1 showed that smokers were 31% more likely to reduce smoking when using an e-cigarette rather than a placebo e-cigarette that delivered no nicotine (odds ratio 1.31 (95% confidence interval 1.02 to 1.58)). For quitting smoking, again measured against placebo, the odds ratio was 2.29 (1.05 to 4.96). Only a single study considered by the Cochrane group compared e-cigarettes with nicotine patches. It concluded that e-cigarettes were better at reducing smoking but made no difference when cessation was the endpoint.

Peter Hajek, professor of clinical psychology at Queen Mary University of London and an author of the review, told a press briefing at the Science Media Centre in London that the results were encouraging. Both of the trials studied had used e-cigarettes with low nicotine delivery, he said, adding, “It is likely that more recent products are more effective, as previous research suggests that higher and faster nicotine delivery facilitates treatment effects.”

Jamie Hartmann-Boyce of the University of Oxford, a coauthor, said, “None of the studies in this review found that smokers who used electronic cigarettes short term, two years or less, had an increased health risk compared to smokers who did not use electronic cigarettes.” The group did not look at any studies of the use of e-cigarettes by non-smokers or any studies that investigated whether e-cigarette use might “renormalise” smoking.

Two members of the group, Peter Hajek and Hayden McRobbie, declared that they had undertaken educational sessions or consultancy work for manufacturers of smoking cessation medicines—interests that, under the current Cochrane commercial sponsorship policy, would have made the review non-compliant. However, when the review began in November 2013 the rules were less stringent, and it did comply. David Tovey, editor in chief of the Cochrane reviews, said that, since the review was already under way, it had been decided not to apply these new rules retrospectively.

John Middleton, vice president for policy at the Faculty of Public Health (FPH), said, “This research is an important contribution to the evidence base for the effectiveness of e-cigarettes as a tool for helping people quit smoking. As the researchers say, we need more of this kind of ‘gold standard’ evidence about e-cigarettes.

“FPH’s position remains that, while e-cigarettes may help smokers who want to quit, we don’t yet have enough evidence of the impact they are having on other people, particularly children and smokers who also use e-cigarettes. There’s good evidence that most people start smoking in their teens and that the most effective way to stop smoking is through NHS ‘quit smoking’ services.”

He added, “It has taken decades of sustained effort to create a society in the UK where smoking is now not seen as the norm. Our concern is that e-cigarettes could reverse this and create a new generation of customers for the tobacco industry, who might otherwise not have started smoking.”


Cite this as: BMJ 2014;349:g7722


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