"The rise in popularity of e-cigarettes in the UK may have resulted in more successful attempts to quit smoking," BBC News reports.
A UK study looking at survey data from England over the past 10 years showed the proportion of successful quit attempts rose in line with the number of smokers using e-cigarettes.
But the number of quit attempts does not seem to be linked to e-cigarette use, and has actually fallen in recent years.
The study, which involved interviews with 170,490 people, can't prove e-cigarettes directly caused the increase in people's successful attempts to quit smoking.
But it does show how trends like e-cigarette use – as well as other factors like the use of other smoking cessation aids, public health campaigns and changes in smoking regulation – may affect smoking rates at a population level.
While research into the safety of e-cigarettes is still ongoing, there's little doubt using these devices is much less harmful than continuing to smoke tobacco.
If you want to stop smoking, evidence shows the best way to do so is to get support, such as counselling, available through NHS stop smoking services.
Other options that can help you quit smoking include nicotine patches, gum and inhalers, as well as medication like varenicline.
Read more about stop smoking treatments.
The study was carried out by researchers from University College London and was funded by Cancer Research UK.
The Guardian gives a good overview of the study, and includes information from a newly published review into the safety and efficacy of e-cigarettes from the Cochrane Collaboration.
The Cochrane review looked at previous studies – not the BMJ study currently hitting the headlines – and concluded: "The quality of the evidence overall is low because it is based on only a small number of studies, although these studies were well conducted. More studies of ECs [electronic cigarettes] are needed."
The Telegraph accurately reported on the study, stating that the long-term safety of e-cigarettes was uncertain.
While this is true, most experts believe they are much less harmful than tobacco. A 2015 evidence review by Public Health England concluded e-cigarettes are "95% less harmful than smoking".
BBC News made a mistake in their reporting of the figures, stating that the study found "the number of smokers who successfully managed to stop smoking increased by just under 1% for every 1% rise in the number of smokers using e-cigarettes".
The actual rise in successful quit attempts was just under 0.1% for each 1% rise in e-cigarette use.
This was a time trend analysis of population trends using data collected from a series of cross-sectional surveys.
It aimed to assess whether changes in the use of e-cigarettes over the years in England is linked to changes in quit attempts, quit rates and the use of other stop smoking services.
This type of study can't prove cause and effect, but it is useful for looking at the potential impact of trends and policies across a whole population, rather than just looking at how they affect individuals.
For example, a trial that looked at whether people were more likely to quit smoking using e-cigarettes can tell us whether e-cigarettes help motivated smokers quit.
But it can't tell you how the growing use of e-cigarettes might affect others – for example, whether people make fewer quit attempts or more young people take up smoking when e-cigarettes are commonly used.
Researchers interviewed households chosen as representative of the English population every three months from 2006 to 2015.
Participants were asked about their smoking habits, including e-cigarette use, whether they'd made any attempts to quit in the last year, and what they'd used to help them quit.
After adjusting their figures to take account of possible confounding factors, the researchers calculated the relationship between the number of people using e-cigarettes either recreationally or to quit smoking, and quit attempt rates, successful quit rates and use of other treatments, such as nicotine replacement therapy.
The data came from both the survey itself – the Smoking Toolkit Study – and information from English NHS stop smoking services, which provided data about the number of people using NHS services.
Researchers took account of changes in health policy, such as the change from centralised to local commissioning of stop smoking services, media campaigns encouraging people to stop smoking, the change in minimum age for buying cigarettes from 16 to 18 in 2007, and the smoking ban indoors in public places, also in 2007.
They calculated the percentage change in outcomes – including quit attempts, successful quit attempts and use of prescribed smoking cessation aids – for each 1% rise in use of e-cigarettes over the period.
About 23% of people in the study had smoked in the past year. Use of e-cigarettes rose from almost no use in 2006 to 21.3% of smokers at the start of 2015.
Use of e-cigarettes to help quit attempts also rose sharply, especially from 2012, with 35% of people attempting to quit in the first quarter of 2015 saying they used e-cigarettes.
The proportion of successful quit attempts also rose, from 10.6% in 2006 to 18.6% in 2015. Researchers said that looking at the trend over time, this could be represented as a 0.098% increase in success rates for every 1% increase in use of e-cigarettes.
But the proportion of people attempting to quit smoking fell over the study period, from about 45.4% of smokers in 2006 to 31.2% at the end of the study.
Looking at the data over time, the researchers said there was no clear association between the increasing use of e-cigarettes and the decreasing number of quit attempts.
The study also showed that declining use of prescription nicotine replacement therapy (NRT) was linked to the increase in e-cigarette use.
The researchers say that if the link between changes in e-cigarette use and successful quit attempts is down to cause and effect, then e-cigarette use in 36% of the 2.6 million quit attempts in 2015 may have resulted in 54,288 successful short-term quit attempts.
They say two-thirds of those people are likely to relapse, meaning an additional 18,000 long-term ex-smokers resulting from the use of e-cigarettes in one year.
They also say the decline in quit attempts during the study period needs further investigation, but possible causes include a big drop in spending on public health stop smoking campaigns in 2010, the financial crisis, and the fact smokers have become gradually less sensitive to messages encouraging them to quit.
Stopping smoking remains the best thing you can possibly do for your health. Anything that can help reduce the number of people who smoke is likely to have a good impact on health.
But although this study found e-cigarette use was linked to an increase in successful quit attempts, there are a number of things to be aware of:
Questions remain about whether e-cigarettes are really safe. While there's still work to do on this, Public Health England estimates the aids are 95% safer than using tobacco cigarettes.
The important thing if you're a smoker is to give yourself the best possible chance of stopping smoking for good.