03:15pm Friday 22 November 2019

More evidence electronic cigarettes help smokers quit

The first Cochrane Review on e-cigarettes for smoking cessation (published today in the Cochrane Library) draws on two randomised trials, one carried out at the National Institute for Health Innovation, The University of Auckland, and one from a research group in Sicily, Italy.  They also drew on evidence from 11 observational studies.

Cochrane Reviews are systematic reviews of primary research in human health care and health policy and are internationally recognised as the highest standard in evidence based health care.

The Review found that while nicotine containing electronic cigarettes was more effective than electronic cigarettes without nicotine (placebo) in helping smokers kick the habit, the results need to be confirmed by more studies.          

“Electronic cigarettes have been around in some form for a number of years, but recently their popularity has increased substantially,” says one of the authors, Associate Professor Chris Bullen, Director of the University of Auckland’s National Institute for Health Innovation.  “They are available in New Zealand, but they are not currently recommended for use by our Ministry of Health.”

Unlike chewing gum and patches, e-cigarettes 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 United Kingdom 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 percent. 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 nine percent of smokers who used electronic cigarettes were able to stop smoking at up to one year. This compared with around four percent 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 percent of electronic cigarette users halved the number of conventional cigarettes. This compared with 28 percent of users who were given the placebos.

Only the University of Auckland trial looked at the effects of electronic cigarettes compared with patches.  This trial suggested similar efficacy of the two treatments. No serious adverse effects occurred over short to mid-term electronic cigarette use.

Professor Peter Hajek, Professor of Clinical Psychology (at Queen Mary University of London), says that “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.”

Research Associate for the Cochrane Tobacco Addiction Group, Jamie Hartmann-Boyce says, “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 (two years or less) had an increased health risk compared to smokers who did not use electronic cigarettes,” she says. “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,” says Ms Hartmann-Boyce. 

Cochrane’s Editor in Chief, David Tovey says this is an important study.

”This review provides a timely reminder of the challenges faced by smokers who find it hard to stop smoking,” he says. “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.”

Full Citation: 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.

Cochrane is a global independent network of researchers, health professionals and consumers of healthcare; carers, advocates and people interested in health. It responds to the challenge of making the vast amounts of evidence generated through research useful for informing decisions about health. Cochrane is a not-for profit organisation with collaborators from over 120 countries working together to produce credible, accessible health information that is free from commercial sponsorship and other conflicts of interest. www.cochrane.org

 For media enquiries email s.phillips@auckland.ac.nz

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