Electronic cigarettes could help smokers kick the habit and do not appear to pose serious side-effects in the short- to mid-term, found a Cochrane Review.
The Guardian reports that the findings come from medical research group the Cochrane Collaboration, which has examined the best available evidence on the devices, together with a new study published in the British Medical Journal (BMJ).
According to the report, it is estimated that about 2m smokers in the UK use electronic cigarettes, but their use has proved controversial, with concerns about safety, the effect on health and the possible impact on the uptake of stop-smoking services.
“What we know from the limited evidence we have available, electronic cigarettes that contain nicotine can help people stop smoking,” said Jamie Hartmann-Boyce of the University of Oxford, a co-author of the Cochrane review and a research associate with the Cochrane Tobacco Addiction Review Group. “In the short- to medium-term we didn’t find any evidence that they were associated with any serious side-effects,” she added.
The advice echoes the finding of the first Cochrane review of the evidence, released in 2014, that looked at 13 studies. Based on two randomised controlled trials involving more than 660 individuals, the previous review found that nicotine-containing e-cigarettes could increase the chance of smokers quitting, with 9% of smokers using such devices stopping smoking for at least six months, compared with 4% of those using e-cigarettes without nicotine. But it was unclear whether e-cigarettes were more effective than other approaches, such as nicotine patches.
The report says that since then, 11 studies have been included in the review, but no further randomised control trial. The Cochrane committee said there was no evidence of serious side-effects from e-cigarette use over a two-year period. “The really good news that came out from this version of the review is that we found a lot more studies under way,” said Hartmann-Boyce. “In the next few years hopefully there will be more evidence out there to strengthen our conclusions.”
The report says the review coincides with the publication in the BMJ of a study that suggests that e-cigarettes can increase success rates for smokers who are attempting to quit. The study looked at survey data from 170,490 individuals aged 16 and older in England between 2006 and 2015, 23% of whom had smoked in the past year, and 21% of whom were current smokers. The study also incorporated data on the use of National Health Service stop smoking services, which encompassed more than 8m smokers.
“We estimate for every 10,000 people who used an e-cigarette to quit, approximately 580 would have quit who wouldn’t have quit otherwise,” said Robert West, co-author of the study and professor of health psychology at University College London.
The authors also estimate that in 2015 e-cigarettes alone may have helped about 18,000 smokers to quit who would not otherwise have quit. What’s more, they say, the devices appear to be linked to a decrease in the use of nicotine replacement therapies on prescription.
But, they add, there was no clear evidence that the devices were prompting more people to give up smoking, or that they had an impact on the use of nicotine replacement therapies bought over the counter, or stop smoking services – an area of interest given a recent decline in use of such services. “There is no evidence that it is making any difference to the rate at which people are trying to stop – it is increasing the rate at which they succeed,” said West.
Background: Electronic cigarettes (ECs) are electronic devices that heat a liquid into an aerosol for inhalation. The liquid usually comprises propylene glycol and glycerol, with or without nicotine and flavours, and stored in disposable or refillable cartridges or a reservoir. Since ECs appeared on the market in 2006 there has been a steady growth in sales. Smokers report using ECs to reduce risks of smoking, but some healthcare organizations, tobacco control advocacy groups and policy makers have been reluctant to encourage smokers to switch to ECs, citing lack of evidence of efficacy and safety. Smokers, healthcare providers and regulators are interested to know if these devices can help smokers quit and if they are safe to use for this purpose. This review is an update of a review first published in 2014.
Objectives: To evaluate the safety and effect of using ECs to help people who smoke achieve long-term smoking abstinence.
Search methods: We searched the Cochrane Tobacco Addiction Group’s Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO for relevant records from 2004 to January 2016, together with reference checking and contact with study authors.
Selection criteria: We included randomized controlled trials (RCTs) in which current smokers (motivated or unmotivated to quit) were randomized to EC or a control condition, and which measured abstinence rates at six months or longer. As the field of EC research is new, we also included cohort follow-up studies with at least six months follow-up. We included randomized cross-over trials, RCTs and cohort follow-up studies that included at least one week of EC use for assessment of adverse events (AEs).
Data collection and analysis: We followed standard Cochrane methods for screening and data extraction. Our main outcome measure was abstinence from smoking after at least six months follow-up, and we used the most rigorous definition available (continuous, biochemically validated, longest follow-up). We used a fixed-effect Mantel-Haenszel model to calculate the risk ratio (RR) with a 95% confidence interval (CI) for each study, and where appropriate we pooled data from these studies in meta-analyses.
Main results: Our searches identified over 1700 records, from which we include 24 completed studies (three RCTs, two of which were eligible for our cessation meta-analysis, and 21 cohort studies). Eleven of these studies are new for this version of the review. We identified 27 ongoing studies. Two RCTs compared EC with placebo (non-nicotine) EC, with a combined sample size of 662 participants. One trial included minimal telephone support and one recruited smokers not intending to quit, and both used early EC models with low nicotine content and poor battery life. We judged the RCTs to be at low risk of bias, but under the GRADE system we rated the overall quality of the evidence for our outcomes as ‘low’ or ‘very low’, because of imprecision due to the small number of trials. A ‘low’ grade means that further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. A ‘very low’ grade means we are very uncertain about the estimate. Participants using an EC were more likely to have abstained from smoking for at least six months compared with participants using placebo EC (RR 2.29, 95% CI 1.05 to 4.96; placebo 4% versus EC 9%; 2 studies; 662 participants. GRADE: low). The one study that compared EC to nicotine patch found no significant difference in six-month abstinence rates, but the confidence intervals do not rule out a clinically important difference (RR 1.26, 95% CI 0.68 to 2.34; 584 participants. GRADE: very low).
Of the included studies, none reported serious adverse events considered related to EC use. The most frequently reported AEs were mouth and throat irritation, most commonly dissipating over time. One RCT provided data on the proportion of participants experiencing any adverse events. The proportion of participants in the study arms experiencing adverse events was similar (ECs vs placebo EC: RR 0.97, 95% CI 0.71 to 1.34 (298 participants); ECs vs patch: RR 0.99, 95% CI 0.81 to 1.22 (456 participants)). The second RCT reported no statistically significant difference in the frequency of AEs at three- or 12-month follow-up between the EC and placebo EC groups, and showed that in all groups the frequency of AEs (with the exception of throat irritation) decreased significantly over time.
Authors’ conclusions: There is evidence from two trials that ECs help smokers to stop smoking in the long term compared with placebo ECs. However, the small number of trials, low event rates and wide confidence intervals around the estimates mean that our confidence in the result is rated ‘low’ by GRADE standards. The lack of difference between the effect of ECs compared with nicotine patches found in one trial is uncertain for similar reasons. None of the included studies (short- to mid-term, up to two years) detected serious adverse events considered possibly related to EC use. The most commonly reported adverse effects were irritation of the mouth and throat. The long-term safety of ECs is unknown. In this update, we found a further 15 ongoing RCTs which appear eligible for this review.
Jaimie Hartmann-Boyce, Hayden McRobbie, Chris Bullen, Rachna Begh, Lindsay F Stead, Peter Hajek
Objectives: To estimate how far changes in the prevalence of electronic cigarette (e-cigarette) use in England have been associated with changes in quit success, quit attempts, and use of licensed medication and behavioural support in quit attempts.
Design: Time series analysis of population trends.
Participants: Participants came from the Smoking Toolkit Study, which involves repeated, cross sectional household surveys of individuals aged 16 years and older in England. Data were aggregated on about 1200 smokers quarterly between 2006 and 2015. Monitoring data were also used from the national behavioural support programme; during the study, 8 029 012 quit dates were set with this programme.
Main outcome measures: Prevalence of e-cigarette use in current smokers and during a quit attempt were used to predict quit success. Prevalence of e-cigarette use in current smokers was used to predict rate of quit attempts. Percentage of quit attempts involving e-cigarette use was also used to predict quit attempts involving use of prescription treatments, nicotine replacement therapy (NRT) on prescription and bought over the counter, and use of behavioural support. Analyses involved adjustment for a range of potential confounders.
Results: The success rate of quit attempts increased by 0.098% (95% confidence interval 0.064 to 0.132; P<0.001) and 0.058% (0.038 to 0.078; P<0.001) for every 1% increase in the prevalence of e-cigarette use by smokers and e-cigarette use during a recent quit attempt, respectively. There was no clear evidence for an association between e-cigarette use and rate of quit attempts (β 0.025; 95% confidence interval −0.035 to 0.085; P=0.41), use of NRT bought over the counter (β 0.006; −0.088 to 0.077; P=0.89), use of prescription treatment (β −0.070; −0.152 to 0.013; P=0.10), or use of behavioural support (β −0.013; −0.102 to 0.077; P=0.78). A negative association was found between e-cigarette use during a recent quit attempt and use of NRT obtained on prescription (β −0.098; −0.189 to −0.007; P=0.04).
Conclusion: Changes in prevalence of e-cigarette use in England have been positively associated with the success rates of quit attempts. No clear association has been found between e-cigarette use and the rate of quit attempts or the use of other quitting aids, except for NRT obtained on prescription, where the association has been negative.
Emma Beard, Robert West, Susan Michie, Jamie Brown
Smoking rates in England have, meanwhile, fallen to the lowest on record, Public Health England (PHE) has said. BBC News reports that in 2015, 16.9% of adults described themselves as smokers, compared with 19.3% in 2012.
Experts say the decrease may be partly thanks to the availability of e-cigarettes.
More than a million people said they vaped as they tried to quit and 700,000 used a licensed nicotine replacement product such as patches or gum.
Out of the 2.5m smokers who tried to kick the habit, a fifth were successful, the report said. According to Public Health England, this is the highest recorded successful quitting rate to date – six years ago the success rate was around one in seven.
At the same time, the report said, prescriptions for smoking cessation aids, such as patches and gum have gone down, while sales of e-cigarettes have gone up.
In 2014/15, the number of prescription items dispensed in England to help people stop smoking was 1.3m, compared to 2m 10 years ago.
Health professionals say the most effective way to quit smoking remains through prescription medication and professional support from free local NHS stop smoking services. Rosanna O’Connor, director of drugs, alcohol, tobacco at Public Health England, said in the report: “The reduction in smoking rates isn’t the result of a single magic bullet but concerted policies over decades.”
Deputy chief medical officer Dr Gina Radford said: “The best thing a smoker can do for their health is to stop smoking. There is more help and support available now than ever before.”
The report said according to experts, taking a complete break from cigarettes for at least 28 days greatly increases the odds of being able to kick the smoking habit for life.
Full BBC News report