The New England Journal of Medicine has just published the results of a randomised controlled trial on the relative efficacy of e-cigarettes v nicotine replacement therapy.

Here are the results and conclusions from the abstract (the full article is paywalled).

Results A total of 886 participants underwent randomization. The 1-year abstinence rate was 18.0% in the e-cigarette group, as compared with 9.9% in the nicotine-replacement group (relative risk, 1.83; 95% confidence interval [CI], 1.30 to 2.58; P<0.001). Among participants with 1-year abstinence, those in the e-cigarette group were more likely than those in the nicotine-replacement group to use their assigned product at 52 weeks (80% [63 of 79 participants] vs. 9% [4 of 44 participants]). Overall, throat or mouth irritation was reported more frequently in the e-cigarette group (65.3%, vs. 51.2% in the nicotine-replacement group) and nausea more frequently in the nicotine-replacement group (37.9%, vs. 31.3% in the e-cigarette group). The e-cigarette group reported greater declines in the incidence of cough and phlegm production from baseline to 52 weeks than did the nicotine-replacement group (relative risk for cough, 0.8; 95% CI, 0.6 to 0.9; relative risk for phlegm, 0.7; 95% CI, 0.6 to 0.9). There were no significant between-group differences in the incidence of wheezing or shortness of breath.

Conclusions E-cigarettes were more effective for smoking cessation than nicotine-replacement therapy, when both products were accompanied by behavioral support.

This study is already causing the predicted outbreak of gushing hyperbole from e-cigarette interests and their urgers.

Professor Martin McKee, from the London School of Hygiene and Tropical Medicine, has shared the following comments about the paper that are very useful.

“The subjects were people who had already decided to attend a stop smoking service. Then, randomisation only began after they had set a quit date. In other words, they were very far from a random sample of smokers. They also excluded existing dual users. [note dual e-cig and cigarette use is by far the most common way that e-cigarettes are used].

Outcome was self-reported use of less than 5 cigarettes from 2 weeks post enrollment to 1 year, and validated, but only by 1 biochemical (CO) test at 1 year, which would only capture very recent smoking.

Among those who did give up, 80% in the e-cig group were still using them, but only 9% of the NRT group were using NRT. Given evidence from other studies, such as the US PATH study, that over longer periods quite a lot of e-cig users relapse, it will be important to look at longer term follow up. (The authors say 80% is “fairly high”!)

They say “Provided that ongoing e-cigarette use has similar effects to long-term NRT…” but then refer to 1988 study. And they say nothing about health risks of e-cigs.

Finally, as they note, this study is inconsistent with 3 previous ones.

So, in summary, I would say:

“This study differs from previous ones in finding that e-cigarettes do seem to be better than NRT at maintaining abstinence, at least for one year, in a highly selected group of people who have already decided to quit and have taken steps to get help with it. Of course, the vast majority of those who quit do so unaided, but, nonetheless, these findings are interesting, although it will be important to see what happens in the longer term. It is, however, important to recognise that it only relates to those who are using e-cigarettes when linked to face-to-face support from a smoking cessation service. It tells us nothing about their use in the wider population of smokers, which is where many of the concerns lie.”

Here’s another comment

“E-cigarettes may be better than the nicotine replacement alternative in the [NEJM] study — but they only helped a minority of participants in the vaping group quit. “In spite of the concerted effort and encouraging findings, it is still disappointing,” said David Liddell Ashley, the previous director of the office of science in the Center for Tobacco Products at FDA [Food & Drug Administration]… So this randomized controlled trial might — and probably should — encourage health professionals to consider e-cigarettes, at least the type shown to be effective in the study, as a tool for their smoking patients. But it also shows e-cigarettes are far from the panacea some suggest they might be.” [Julia Belluz. Study: Vaping helps smokers quit. Sort of. Vox] 

Behavioural support: little real world relevance

To this I would emphasie that the participants in the trial received not only e-cigarettes or NRT, but they self-selected to attend a quit smoking service and received “behavioural support”.  This means these subjects were very different to random e-cigarette or NRT users in the English community, the great majority of whom do not elect to attend such services.

In Australia, despite the quitline phone number being on  every cigarette pack and it being hammered in many quit smoking campaign ads, only 3.6% of smokers ever called the quitline over a year. Far fewer are interested in attending “behavioural support” sessions. So this paper has very important limitations in its relevance for debates about whether e-cigarettes (or NRT) can assist people to quit under conditions of real world use.

We know from recent real world longitudinal studies of people who vape in the USA that e-cigarette users actually do worse with quitting than those who use other forms of smoking cessation aids, and particularly those who quit unaided. I covered this in an earlier blog here.

We also know that over-the-counter NRT, used without support in the normal way that nearly all users use it, is not effective. See for example here  (“The use of NRT bought over the counter was associated with a lower odds of abstinence (odds ratio, 0.68; 95% CI, 0.49-0.94).). In other words, using NRT like this might actually prevent quitting. Big Tobacco, now with major investments in e-cigs and heat-not-burn products, will be praying the same thing is true for e-cigs. And if they are wise investors, also very confident that the net effect of e-cigarette proliferation will be to keep far more people in smoking than are tipped  out of it, and that it will provide nicotine addiction training wheels to many children who have never smoked and probably never would have.