Electronic cigarette users followed over a year reduced or quit using tobacco cigarettes in large numbers and were less prone to resume smoking, at least in the short term.
Experts continue to debate whether or not "e-cigs" are smoking-cessation tools or just leisure products. The electronic vaporizers use cartridges of liquid nicotine to deliver a flavored nicotine-laced vapor without the byproducts of burning tobacco in traditional cigarettes.
"Our results may not be generalizable to all vapers," Jean-Francois Etter said, using the slang for vaporizer users. "We had a majority of ex-smokers at baseline whereas in the general population, most vapers are current smokers," he told Reuters Health.
Etter led the study at the Institute of Social and Preventive Medicine at the University of Geneva in Switzerland. The results were published in Addictive Behaviors.
A few small studies have found that e-cigarettes seemed to help smokers quit using tobacco or at least to smoke fewer traditional cigarettes. But there have been no long-term studies of how people actually use e-cigarettes, so experts are still unsure.
The researchers posted a questionnaire on a French stop-smoking website and asked sites selling e-cigs to link to the questionnaire. Most "vapers" buy their e-cigs online.
The e-cig users recruited answered a baseline questionnaire, another one a month later and a third one year later. Questions covered e-cigarette use, tobacco use and the date of quitting tobacco, if one applied.
Of more than 1000 original recruits, 367 responded to all three surveys.
For those who had quit smoking already and were using e-cigarettes instead, six percent had relapsed to tobacco after one month. That number was stable after one year.
Of those who were smoking and using e-cigarettes when the study began, 22 percent had quit smoking tobacco after a month and 46 percent had quit after a year. That group averaged 11.3 tobacco cigarettes daily at the beginning of the study and six cigarettes per day after one month.
This was just an exploratory study and will need confirmation from follow-up studies, Etter said.
"This suggests that e-cigs may help them quit, but our results need to be interpreted with caution, because of the dropout rate at follow-up and the fact that our sample is not representative of all vapers," he said.
In the short-term, e-cigs appear not to carry any health risks of their own, he said. But researchers still don't know the long-term health effects of inhaling the common solvent glycol and food flavoring over many years.
E-cigarettes don't need to be 100 percent safe, he said, they only need to be significantly safer than tobacco cigarettes because they are primarily used by cigarette smokers. Of the three studies that have investigated e-cig users, none of the daily vapers were non-smokers.
Even though the evidence is still thin, Etter believes smokers should use e-cigarettes as quit-smoking aids, and doctors should recommend them. But the products should not be treated as medical devices or drugs, even though they may have therapeutic benefit for patients, he said.
"Internet surveys are more likely to attract people who had a positive experience with e-cigarettes," professor Peter Hajek said. "The study is nevertheless innovative in that it did not just ask for a one-off information as a number of previous studies did, but it followed the e-cigarette users up to see what happens to their e-cig use and to their smoking one year later," he said.
Hajek is director of the Tobacco Dependence Research Unit at Barts and The London School of Medicine and Dentistry in London, UK. He was not involved in this study.
The new study adds to the evidence that e-cigarettes can help smokers quit or cut down, he said.
"There are two products competing for smokers' business," Hajek said. "One kills half the users, the other one is at least an order of magnitude safer," he said. "It makes little sense to try to cripple the safer one so the deadly one maintains the market monopoly."