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Emerging evidence supports their use as a cessation aid but authors call for further research

Findings suggest electronic cigarettes with nicotine help people stop or reduce smoking when compared to electronic cigarettes without nicotine, but more studies are needed.
- Jamie Hartmann-Boyce, Nuffield Department of Primary Care Health Sciences, University of Oxford.

Electronic cigarettes can help smokers to stop smoking or significantly reduce their consumption, according to new evidence published in the Cochrane Database of Systematic Reviews.

The review draws on data from two randomised trials and found that while nicotine-containing electronic cigarettes were more effective than a non-nicotine placebo in helping smokers to kick the habit, the results need to be confirmed by further research.

Electronic cigarettes are used by many smokers and have been available for a number of years, with their popularity increasing substantially. Yet little has been known about how effective they are at helping people to stop, or their long-term effects.

Smoking is a major global health problem, is costly and addictive. Despite many smokers wanting to stop, few succeed in the long term.

A team of researchers from the UK and New Zealand studied two randomised trials that had analysed data from 662 current smokers. The researchers looked at the effects of electronic cigarettes on quit rates and the number of people who were able to reduce how many cigarettes they smoked by at least 50%. They also looked at any adverse effects reported by electronic cigarette users. The team also considered evidence from 11 observational studies.

While the results demonstrate that electronic cigarette use is beneficial as a cessation aid for smokers, they are limited by the small number of trials and the limited sample of people who were analysed in the studies.

About 9% of smokers who used electronic cigarettes were able to stop smoking at up to one year. This compared with around 4% of smokers who used the nicotine-free electronic cigarettes.

36% of electronic cigarette users halved the number of conventional cigarettes, but had not quit. This compared with 28% of users who were given placebos.

Only one trial looked at the effects of electronic cigarettes compared with patches, which suggests similar efficacy of the two.

The studies also show that using electronic cigarettes for up to two years causes no serious adverse health effects.

In light of this emerging evidence, the authors have cautioned that further research into their effectiveness is needed.

Cochrane’s Editor in Chief, David Tovey said this is an important study:

“This review provides a timely reminder of the challenges faced by smokers who find it hard to stop smoking. The results so far need to be strengthened with further comparisons between electronic cigarettes and other traditional ways of stopping smoking such as chewing gum and patches, and evidence on long-term safety.”

Study author, Jamie Hartmann-Boyce (pictured), a research associate for the Cochrane Tobacco Addition Group in the Nuffield Department of Primary Care Health Sciences, University of Oxford said:

“Electronic cigarettes have become popular with smokers who want to reduce the risk of smoking. None of the studies in this review found that smokers who used electronic cigarettes short-term (2 years or less) had an increased health risk compared to smokers who did not use electronic cigarettes. We did not find any evidence from observational studies that people who used electronic cigarettes at the same time as using regular cigarettes were less likely to quit smoking. Findings suggest electronic cigarettes with nicotine help people stop or reduce smoking when compared to electronic cigarettes without nicotine, but more studies are needed.” 

Study author, and Professor of Clinical Psychology Peter Hajek, Queen Mary University of London commented:

“Although our confidence in the effects of electronic cigarettes as smoking cessation interventions is limited because of the small number of trials, the results are encouraging. Both trials used electronic cigarettes with low nicotine delivery and it is likely that more recent products are more effective as previous research suggests that higher and faster nicotine delivery facilitates treatment effects. Several ongoing studies will help to answer the question more fully.”

Watch: Channel 4 News Can e-cigarettes help you quit smoking? 17 December

Listen: BBC Radio 4 Today (1:31:30), 17 December  

Paper reference:

McRobbie H, Bullen C, Hartmann-Boyce J, Hajek P. 
Electronic cigarettes for smoking cessation and reduction. 
Cochrane Database of Systematic Reviews 2014, Issue 12. Art. No.: CD010216. DOI: 0.1002/14651858.CD010216.pub2.


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