17 Mar, 14 | by BMJ
The public health appeal of vaping that emboldens its advocates to sanctimoniously taunt anyone unconvinced by their evangelism as callous “quit or die” moralists is that e-cigarettes are spectacularly promising as a way of quitting smoking. Aware that many vapers also continue to smoke, they point to the seemingly undeniable logic of “every cigarette forgone to vaping is harm reducing.”
So what’s the status of these two central claims for the health virtues of vaping?
Vapers’ social media and chat rooms are brimming with ex-smokers jubilant that vaping has enabled them to permanently quit smoking. That’s undeniably good news for them. But just as home beer brewing or whiskey appreciation societies are small, self-selecting, fractions of all those who enjoy beer or Scotch, vaping communities are highly unlikely to be representative of all vapers. There are an estimated three million smokers in Australia and some 17% of smokers have ever tried vaping (some 510,000), despite sales of nicotine juice being banned. But Aussie Vapers, an anonymous chat room, has only 6936 members, of which just 1017 are active.
Claims about vaping and smoking cessation from studies of survey volunteers from such communities are therefore of low value in estimating potential population impacts across all e-cigarette users, limitations generally acknowledged in such papers.
Four clinical trials and three population based studies have so far reported on cessation. Two trials had very small samples, but one of the larger ones, involving Italian smokers not intending to quit, found an 8.7% smoking cessation rate at one year. The other from New Zealand, involving smokers wanting to quit, found no statistically significant differences in continuous smoking abstinence at six months between e-cigarette, nicotine patch, and non-nicotine e-cigarette arms of the trial.
Vapers emphasise that the New Zealand trial involves “generation 1” cigalikes which they argue to be far inferior in nicotine delivery to more recent systems. But to date, no population sourced evidence is available to test these anecdotal claims.
A four country cohort study found that while 85% of smokers who had used e-cigarettes were using them to quit, one to two years later these smokers were no more likely to have quit than smokers not using them. A US study of callers to six state quitlines (i.e. those already motivated to quit) found that those smokers who reported any use of e-cigarettes were significantly less likely to quit than those who had never used them.
The most recent and important data from a “real world” population study are from England, and have been acclaimed in many vaping chat rooms. It found vapers “were more likely still to be abstinent than either those who used NRT bought over-the-counter (OR=2.23, 95%CI=1.67- 2.97, 19.9% vs. 10.0%) or no aid (OR=1.40, 95%CI=1.07-1.82, 19.9% vs. 15.1%). The adjusted odds of non-smoking in users of e-cigarettes were 1.66 (95%CI=1.17-2.6) times higher compared with users of NRT bought over-the-counter and 1.60 (95%CI=1.15-2.23) times higher compared with those using no aid.”
Vaping advocates are frequently contemptuous of nicotine therapy, routinely insinuating that anyone circumspect about the benefits of vaping has pharmaceutical industry ties. Yet putting these studies together, a picture emerges of e-cigarettes being anything from a factor that might reduce quit rates, to one that produces a modest improvement in quitting over doing nothing more than deciding to quit. Far from being just as or slightly more “effective” than OTC NRT or unassisted cessation, it might be said that e-cigarettes are just as disappointing.
While there is strong evidence for a causal association between early uptake, amount smoked, and duration (pack years) of smoking, the evidence on “reverse engineering” harm by continuing to smoke while cutting back is far from strong.
A Norwegian cohort of 51,210 people followed from the 1970s until 2003 found, “no evidence that smokers who cut down their daily cigarette consumption by >50% reduce their risk of premature death significantly.” A Scottish study of two cohorts followed from the 1970s to 2010 found no evidence of reduced mortality in reducers, but clear evidence in quitters and concluded, “that reducing cigarette consumption should not be promoted as a means of reducing mortality.” The largest study, from Korea involved 479,156 men followed for 11 years. It found no association between smoking reduction and all cancer risk, but a significant decrease in risk of lung cancer, with the size of risk reduction “disproportionately smaller than expected.”
A 2007 systematic review of the evidence on the health impact of reduction, which included none of the above large studies, noted that most studies examined reductions of more than 50% in smokers. It found, “a substantial reduction in smoking seems to have a small health benefit, but more studies are needed to determine the long term effects of smoking reduction.” The New Zealand trial saw 57% of e-cigarette users reducing by more than 50%, and the four country study saw average daily consumption reduce by just 19%. Substantial reduction in smoking via vaping is clearly possible, but dual use with clinically unimportant reductions looms as a more likely scenario.
The impact of any smoking cessation policy or strategy is a function of its effectiveness multiplied by its reach. So here, there is reason for some optimism. The rapid growth in e-cigarette use in some nations, despite the very modest early results on quitting described above may nonetheless translate into a large number of ex-smokers across the population who attribute their quitting to e-cigarettes. But that would be only part of the story. What proportion of these quitters would have stopped anyway had e-cigarettes not been available? Would we just be seeing substitution of cessation methods? Would the overall cessation volume rise? How many vapers who do not quit and become dual users might have prevaricated and stayed smoking because they vaped?
The net public health impact of widespread vaping will see many benefits, but many who otherwise may have quit will be held in dual use having bought the hype that smoking a bit less is seriously risk reducing. Most vapers do not quit cigarettes (in the English study, 80% of vapers were also smoking). Continuing to smoke, many will die early from smoking caused diseases. And then we come to the potential for both vaping uptake and graduation into smoking among teenagers who may have otherwise never used any form of nicotine delivery device (see next blog in this series—due online shortly).
Competing interests: I have read and understood the BMJ Group policy on declaration of interests and have no relevant interests to declare.
Simon Chapman AO PhD FASSA is professor of public health at the University of Sydney and for 17 years was deputy editor and editor of the BMJ’s Tobacco Control.