Do electronic cigarettes help smokers to quit? Yes, but there is more to the story.

New Cochrane review finds emerging evidence that smokers who use electronic cigarettes can stop or reduce their smoking.

The first Cochrane review on this subject published today in the Cochrane Library gives some early insights in to electronic cigarettes as an aid to stopping smoking and reducing consumption. The review draws on two randomised trials and found that while nicotine containing electronic cigarettes were more effective than electronic cigarettes without nicotine (placebo) in helping smokers kick the habit, the results need to be confirmed by more studies. Smoking is a major global health problem, is costly and is highly addictive. Despite many smokers wanting to stop, few succeed in the long-term. One of the most widely used strategies to help combat the cravings associated with nicotine addiction is to deliver nicotine by patches and chewing gum.

Electronic cigarettes have been around in some form for a number of years but recently their popularity has increased substantially. Unlike chewing gum and patches, they mimic the experience of cigarette smoking because they are hand-held and generate a smoke-like vapour when used. They provide smokers with a nicotine 'hit' and help to recreate similar sensations of smoking without exposing them or others to the smoke from conventional cigarettes. They are used by many smokers but little has been known about how effective they are at helping people to stop, nor their long term effects.

The team of researchers from the UK and New Zealand found 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 the number of 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.

The results show beneficial effects of electronic cigarettes, but are limited by the small number of trials and 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. When the researchers looked at the data on reducing cigarettes in people who had not quit, they found that 36% of electronic cigarette users halved the number of conventional cigarettes. This compared with 28% of users who were given the placebos. Only one of the trials looked at the effects of electronic cigarettes compared with patches and this suggests similar efficacy of the two treatments. No serious adverse effects occurred over short to mid-term electronic cigarette use.

Author, and Professor of Clinical Psychology Peter Hajek, 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."

Author, Jamie Hartmann-Boyce 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."

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."