Electronic cigarettes and smoking cessation: an interview with Professor Peter Hajek

Prof. Peter HajekTHOUGHT LEADERS SERIES...insight from the world’s leading experts

How long have electronic cigarettes been around for and why do you think their popularity has increased substantially in recent years?

The electronic cigarette has been invented by Chinese pharmacist Hon Lik in 2003. The rise in electronic cigarettes (EC) popularity was initially a grass root phenomenon. EC are estimated to be at least 95% safer than cigarettes and they appeal to smokers who cannot or do not want to stop smoking, but who want to reduce the risks smoking poses to their health.

The tobacco industry joined this market only in 2012, when they realised that EC can make conventional cigarettes obsolete and that they need to hedge their bets to avoid the ‘Kodak moment’ – a watershed when a new technology destroys the old business model.

Regarding EC popularity over the last year or so, it has actually stalled or even declined. It could be that smokers who find a slower and lower nicotine delivery device satisfactory have already switched to EC, but a much more likely explanation for this is the on-going anti-EC campaign.

Tobacco industry and certain public health activists are trying to deter smokers from switching to EC. The emerging evidence on EC contents, which continues to confirm that EC are orders of magnitude safer than cigarettes, is being misreported to make EC appear unsafe.

Switching from cigarettes to EC requires effort and media stories suggesting that the switch is not going to be all that helpful seem to be encouraging smokers to stick to the conventional cigarettes.

Why has little been known about how effective electronic cigarettes are at helping people to stop smoking?

EC are a consumer product rather than a medicine and from this point of view, asking about their efficacy is like asking whether cars with better safety features have been effective in helping people to stop using cars which were less safe. They did, but only in a way any improved product replaces the inferior one.

The market success of EC shows that for many smokers, EC have been ‘effective’ in replacing cigarettes, but up to now, only a small fraction of smokers have made the switch.

There is a legitimate question though asking whether EC offered pro-actively help smokers to stop or reduce their smoke intake. To provide an answer, randomised controlled trials are needed.

It is not surprising that there are not many of those available yet. Such trials are expensive and normally funded by manufacturers of the medications which are being evaluated. The expenditure is justified because the medicine cannot be sold unless proven effective in this particular way.

In the case of EC, manufacturers are not trying to enter the medicine market, although various regulatory bodies are attempting to force them to do so. Randomised trials of EC thus had to be funded by someone else.

Government bodies which fund medical research are now realising the huge potential benefit EC offer and such studies are beginning to appear, but it has been a slow process.

Please can you outline the recent Cochrane review that looked at trials on the effects of electronic cigarettes on quit rates?

We found three small cohort studies which provided smokers with EC and followed them up to assess changes in their smoking and to assess safety of EC use. They all reported impressive results but with no control groups, the effects of EC on smoking cessation and reduction are difficult to interpret.

The substance of the review rests with two randomised trials which followed participants for at least 6 months. Both trials compared the efficacy of EC with and without nicotine (placebo EC), with one of them also comparing both types of EC with nicotine patches.

Both of these trials provided a tough and conservative test of EC efficacy. Firstly, both used EC with low nicotine delivery which are rarely used any more. We know that the efficacy of nicotine replacement treatments improves with better nicotine delivery.

Secondly, one trial focused on smokers not intending to quit, and the other posted EC to smokers and provided no other support apart from an advice to call a local Quitline, which only a fraction of participants did.

We know that the efficacy of stop smoking treatments is limited in smokers not intending to quit, and it is also low if there is no accompanying support available.

As expected, the quit rates in both trials were low, but in the combined results, nicotine containing EC were significantly more effective than placebo EC. They were more effective both in terms of biochemically validated long-term abstinence and, in those participants who did not manage to stop smoking altogether, in terms of the proportion of smokers who reported reducing their cigarette consumption by 50% or more.

The effects of EC did not differ from the effects of nicotine patches. EC use generated no safety concerns.

What were the main takeaways from this review?

The main conclusion is that the limited evidence we have shows that EC help smokers quit and that over short to mid-term (when used for up to 1.5 years) no safety concerns emerged.

However, we emphasize that our confidence in these results is low. This concerns primarily the size of the effect. The risk ratio was about 2.3, suggesting that nicotine containing EC roughly double the chance of a smoker to successfully stop using conventional cigarettes.

There is little doubt that replacing nicotine from cigarettes with nicotine from an alternative source helps smokers quit – over 100 placebo controlled trials of various nicotine replacement treatments have proven this beyond reasonable doubt, and so we are confident that EC delivering nicotine help as well.

We are unsure however about how big this effect is when standard stop-smoking support is provided and modern EC with better nicotine delivery are used.

Regarding adverse events, the uncertainty is related to the relatively small number of smokers studied so far. It is possible that some rare side effects in smokers with specific vulnerabilities may yet emerge.

Were you surprised by these results?

Not really, as noted above, we know that nicotine replacement treatments are effective, and there is little reason to expect that EC use over short to mid-term would pose any health risks.

In what way were the results limited and what further research is needed?

The results are limited primarily because of the small number of trials and the use of obsolete EC products. The main outstanding research need includes further trials comparing the efficacy of EC with the efficacy of other stop-smoking treatments. Several such trials are currently planned or already underway.

It is one of the great virtues of Cochrane meta-analyses that they get updated when new evidence comes along. All future data from randomised controlled trials with long-term follow-up will get included and will sharpen our effect estimates.

How much is currently known about the long term effects of electronic cigarettes and how does this compare to traditional ways of stopping smoking such as chewing gum and patches?

Nicotine replacement treatments such as nicotine chewing gum and patches can be used long term with little ill effects. The review did not detect any safety concerns when EC are used over weeks to months, but it did not attempt to evaluate any long-term safety issues.

In terms of the proportion of people who successfully stopped smoking and continued to use EC, in the two trials only 20%-30% of successful quitters were still using EC at the longest follow up. This is similar to what we see with medicinal nicotine replacement products.

Some smokers need the crutch of nicotine replacement for longer, but outside pregnancy, this poses negligible health risks.  

What do you think the future holds for electronic cigarettes and smoking cessation?

I think the future of EC is uncertain. The anti-EC campaigners have been successful in initiating regulatory requirements which will reduce the competitiveness of EC with conventional cigarettes, slow-down or halt their further development, and deter smokers from making the switch.

Without such measures, I would expect EC to evolve within the next few years into a product which provides the majority of smokers with what they want from their cigarettes. Once that stage is reached, in countries which allow EC use, smoking would virtually disappear. The public health benefits would be huge.

With the proposed regulatory measures in place however, EC are likely to survive only as a tobacco industry product because the tobacco industry will be the only manufacturer able to cope with the cost of the new regulatory hurdles.

As a result of this, EC evolution is likely to slow-down or stop, EC price advantage will disappear, and EC may become just a niche product used by a small proportion of nicotine users, with the vast majority continuing to smoke. We are at a danger of squandering a historical public health opportunity.

Where can readers find more information?

For a general review of what is known about EC written by an international team of EC researchers, see:  

Hajek P, Etter JF, Benowitz N, Eissenberg T, McRobbie H (2014) Electronic cigarettes: use, content, safety, effects on smokers, and potential for harm and benefit. Addiction, doi:10.1111/add.12659

For a discussion on how relevant evidence gets misreported for political ends, see:

West R (2014) Electronic cigarettes: getting the science right and communicating it accurately. Addiction, http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291360-0443/homepage/electronic_cigarettes.htm

McNeill A, Bates C, Etter JF, Farsalinos C, Hajek P, leHouezec J, McRobbie H. (2014) A critique of a WHO-commissioned report and associated article on electronic cigarettes. Addiction Sep 5. doi: 10.1111/add.12730.

About Professor Peter Hajek

Peter Hajek is Director of the Health and Lifestyle Research Unit at Wolfson Institute of Preventive Medicine, Queen Mary University of London. His research is concerned primarily with understanding addictive behaviours, and developing and evaluating both behavioural and pharmacological treatments for dependent smokers and for people with weight problems.

He authored or co-authored over 300 publications. A number of his research findings influenced international clinical practice and policy including NICE and other clinical practice guidelines and the establishment of national stop-smoking services in the UK and other countries.

His research into safety and efficacy of EC was funded by MHRA, NIHR and UKCTAS. He has no links with any EC manufacturers.

April Cashin-Garbutt

Written by

April Cashin-Garbutt

April graduated with a first-class honours degree in Natural Sciences from Pembroke College, University of Cambridge. During her time as Editor-in-Chief, News-Medical (2012-2017), she kickstarted the content production process and helped to grow the website readership to over 60 million visitors per year. Through interviewing global thought leaders in medicine and life sciences, including Nobel laureates, April developed a passion for neuroscience and now works at the Sainsbury Wellcome Centre for Neural Circuits and Behaviour, located within UCL.


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  1. Tim Swan Tim Swan United States says:

    Another win for the EC industry.  Most of this is common sense which most use in switching from the analogs to the electric version.  The decline in sales of the phase I e cigs was expected with the growing popularity of the newer tanks and battery versions.  Vapers’ are making the switch because of the higher level of pleasure derived from the much improved mechanics.  Also, the phase I devices consistently fell short of what they were advertising in terms of length of use and flavor.

    • IMSiegfried Siegfried IMSiegfried Siegfried United States says:

      What you wrote isn't entirely accurate. As stated by Professor Hajek and Robert West (in the comment below yours) the problem is anti-tobacco advocates have managed to convince smokers that e-cigs are no less harmful than smoking and that's why there's a decline in smokers switching at all, rather than it not being to a first generation e-cig. I think Dr. Farsalinos stated the decline is as much as 30% in three years, if I remember correctly. Either way, there are links at the bottom of this article to a couple more articles about how relevant evidence gets misreported for political ends that would explain how big the decline has been.

      When even vapers agree to vaping bans where-ever smoking is banned you know anti-tobacco advocates are winning.

  2. Robert West Robert West United Kingdom says:

    Professor Hajek is one of the world's leading experts in smoking cessation and is in no small part responsible for the support that is now available in many countries, especially the UK. His analysis is sound. It is ironic that some public health activists who are mostly not experts in this topic are doing the tobacco industry's dirty work in trying to stamp out this threat to their monopoly on nicotine dependence.

  3. Hans Schmidt Hans Schmidt Germany says:

    Dear Prof Hajek, you talk about "a slower and lower nicotine delivery device". Vapers and smokers self-titrate their nicotine intake. If a vaper needs a quick and high nicotine hit he/she will use a strong liquid and inhale deeply in the lungs. Just like a smoker.
    Have you ever tried a 36mg nicotine per milliliter liquid? Or a 150 Watt mod?

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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