The more that vaping takes hold in England, the better the odds that smokers there will succeed in their attempts to stop using regular cigarettes.
These parallel trends, reported Wednesday in the BMJ medical journal, don't prove that electronic cigarettes help smokers kick the habit. But that possibility is looking more and more likely, experts said.
Smoking prevalence in the United Kingdom fell significantly from 2014 to 2015, and that's a sign that something over there is working, according to an editorial that accompanies the study.
"Successful quitting through substitution with e-cigarettes is one likely major contributor," wrote John Britton, director of the UK Center for Tobacco and Alcohol Studies at the University of Nottingham. "The challenge for public health is to embrace the potential of this new technology and put it to full use."
Health experts in England have been contemplating the smoking-cessation benefits of e-cigarettes for several years. A previous study of English smokers found that would-be quitters who vaped were about 60% more likely to succeed compared with smokers who tried to go cold turkey or used nicotine replacement products, like patches or gum.
This time, researchers from University College London wanted to see whether the prevalence of e-cigarette use among active smokers — and especially among those trying to quit — had anything to do with a smoker's likelihood of kicking the habit.
The researchers examined data on nearly 80,000 smokers who took part in England's Smoking Toolkit Study from 2006 to 2015. In the last quarter of 2006, 10.6% of quit attempts succeeded. By the first quarter of 2015, the success rate had climbed to 18.6%, according to the study.
Meanwhile, the proportion of smokers who also vaped increased from virtually zero to 21.3% during the same period, the researchers found.
Vaping was even more popular among smokers who were trying to quit, with 35% of them using the electronic devices in 2015. That embrace of e-cigarettes coincided with a drop in use of more conventional nicotine replacement products.
The researchers found no conclusive link between vaping and attempts to quit smoking. But their calculations showed that "for every 1% increase in e-cigarette use, the success of quit attempts increased by 0.098%," according to the study. In addition, for every 1% increase in vaping among smokers trying to quit, the success rate of quit attempts rose by 0.058%, the study said.
If e-cigarette use really is helping smokers quit, that means 54,288 people in England who were able to stop smoking in 2015 can thank vaping for their success. Although roughly two-thirds of them can be expected to fall off the wagon, that still leaves about 18,000 "long term ex-smokers" as a result of e-cigarette use, the study authors wrote.
It may not sound like much of an improvement, but it's "clinically significant because of the huge health gains from stopping smoking," the researchers wrote. "A 40-year-old smoker who quits permanently can expect to gain nine life years compared with a continuing smoker."
In the early days of vaping, health experts worried that e-cigarettes would encourage smokers to keep on smoking by providing a socially acceptable substitute in venues where regular cigarettes were banned. But the new study suggests that the opposite is true, Britton wrote in the editorial.
(One of the study authors, health psychologist Robert West, has served as a consultant to companies that make smoking cessation products but doesn't accept money from tobacco or e-cigarette companies. Two others coauthors, Emma Beard and Jamie Brown, disclosed that they have received funding from Pfizer.)
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