E-cigarettes are almost twice as effective as nicotine replacement for smoking cessation assistance, the study suggests.
The study found that 18% of smokers used them to quit smoking after a year, compared to 9.9% of those who used substitution drugs.
Studying the 886 smoker is the first test to check if modern e-cigarettes are effective.
Researchers hope that their findings will lead to routine smoking smoking devices.
Public health in England has already demanded that e-cigarettes be made available to the NHS within five years, suggesting research suggesting that at least 95% less harmful than cigarettes.
However, so far, there has been no evidence of how effective they are as smoking cessation tools.
Principal Investigator Prof. Peter Hajek, of London's Queen Mary University, said: "Although a large number of smokers reported having successfully stopped smoking with the help of e-cigarettes, health professionals reluctantly recommend their use due to the lack of clear evidence from randomized controlled trials.
"This will probably change."
"Accelerate" smoking reduction
Smoking attorneys and early queues did not quit smoking queues at the NHS and were randomly divided into two groups:
- those who received nicotine-replacement treatment of their choice, including gum, patches, lozenges, sprays and inhalers, or a combination of treatments, up to three months
- those who get an starter package with one or two bottles of e-liquid (supply two to four weeks)
Those who received e-cigarettes have been encouraged to buy future supplies of their own choice of strength and taste, and all participants received a supportive support for at least four weeks weekly.
Study, published in the New England Journal of Medicine, showed that apart from having higher rates of smoking cessation, more e-cigarette users reduced smoking by at least 50%.
E-cigarettes also provided greater satisfaction and were rated as more useful than nicotine-replacement therapy.
A higher proportion of those who used the appliances experienced mouth and throat irritation (65% to 51%), although people with nicotine replacement therapy were more likely to experience nausea (38% versus 31%). These effects are mostly mild.
Prof. Hajek voiced hope that the results of this study will result in the smoking cessation service offering to the customers an e-cigarette starter package and guidelines on how to get it, after which they could pay their own supplies.
"This could ultimately further speed up the reduction in smoking and smoking-related diseases," said Dunja Przulj, the second author of the study, also from Queen Mary University in London.
The study has some limitations.
Since people knew what treatment they received – unlike "blinded" as in most randomized controlled trials – it is possible that participants could replace nicotine as an inferior option and make less effort to quit smoking, the authors say.
They also said that more work is needed to determine if their results apply to countries outside the UK and less dependent smokers.
The study was followed by an independent review of e-cigarette evidence, published by Public Health England, released in February last year, concluding that there is "immense evidence" that is far safer than smoking and "negligible risk for observers."
However, some experts say e-cigarettes, though safer than normal cigarettes, are not harmless, and their long-term effects are not yet known.
Responding to this latest survey, Public Health in England stated: "All smoking stoppers should greet smokers who want to stop using e-cigarettes."