Electronic cigarettes are more effective at helping smokers to quit tobacco when they contain nicotine, a review of studies has found.
The review by the international Cochrane Collaboration includes two trials in which smokers were randomised to groups using different kinds of electronic cigarettes or quit-smoking therapy. One of these trials was based at Auckland University, the other in Italy.
An e-cigarettes is a battery-powered device which, when the user takes a drag, produces a vapour. They can be run with or without nicotine in the vapour. Nicotine is the main addictive component of tobacco smoke. The vapour contains much lower levels of toxins than tobacco smoke. Tobacco control researchers are divided on whether e-cigarettes may become a useful quit-smoking device or a new gateway for young people to tobacco smoking.
Dr Chris Bullen, an author of the Cochrane review and a researcher on the Auckland University trial, which followed participants for six months, said the trial found that 7.3 per cent of those using e-cigarettes containing nicotine had quit tobacco. The quit rate was 5.8 per cent in the nicotine patches group and 4.1 per cent among those using non-nicotine e-cigarettes.
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The nicotine e-cigarettes were a low-nicotine version, delivering just 19 micrograms per puff, compared with 49 micrograms for the highest-nicotine version on the market at the time, and 100 micrograms per puff on a tobacco cigarette. The use of low-nicotine e-cigarettes was thought by the New Zealand researchers to be the reason for a quit rate much lower than expected and statistically no different from the quit rate on patches.
Dr Bullen said the Italian trial used high- and medium-nicotine e-cigarettes. It found that at one year, 13 per cent on the high-nicotine version had quit, compared with 9 per cent on the medium-nicotine version and 4 per cent on the non-nicotine e-cigarettes.
Pooled trial data on the effect on reducing tobacco consumption showed that 36 per cent of nicotine e-cigarette users halved the number of tobacco cigarettes they consumed, compared with 28 per cent of those using the non-nicotine e-cigarettes.
"Findings suggest electronic cigarettes with nicotine help people stop or reduce smoking when compared to electronic cigarettes without nicotine, but more studies are needed," said Jamie Hartmann-Boyce, a research associate for the Cochrane Tobacco Addiction Group.