For several years vaping advocates have promoted e-cigarettes as a tool to help smokers quit and greatly reduce harm, with one study making the ludicrous claim that e-cigarettes had a quit rate of 81%. The data here was obtained from self-selected participants in vaping advocates' chat rooms. It's unclear how many had a commercial interest in e-cigarettes.
Eleven published studies have now investigated how people who vape compare with smokers who don't when it comes to quitting. Stanton Glantz from the University of California has meta-analysed these studies and found that smokers who vape are 30 per cent less likely to quit smoking than smokers who don't.
Critics have pointed out that all these studies have lumped together daily users with less-than-daily users. This last group would include those who have tried vaping only occasionally or out of curiosity and so they'd be far less likely to be vaping in an attempt to quit smoking.
But today's Addiction paper addresses this criticism by dividing participants into three groups: those who attempted to quit without the use of e-cigarettes; those who used e-cigarettes occasionally (less than daily); and those who used e-cigarettes daily.
Cutting back
There were three principal findings from the study. The first, predictably, was that far more smokers who used e-cigarettes daily were trying to quit smoking than those who used them less than daily. This is a bit like discovering that people who drink diet colas are trying to reduce their dietary calories.
The second is that daily vapers reduced the number of cigarettes they smoke more than those who didn't vape every day:
Smokers using e-cigarettes daily when followed up were more likely [than less-than-daily vapers] to have achieved at least 50 per cent reduction in tobacco cigarette consumption from baseline.
That may be so but the proportions making these substantial reductions were modest. Of those vaping every day, only 13.9 per cent reduced their smoking by at least half. So more than 86% of daily vapers are not making substantial reductions: they are vaping daily and often smoking as much as they always have. These long-term dual users are wonderful news for tobacco companies that are now selling cigarettes and e-cigarettes.
After 12 months, nearly 6 per cent of smokers not using e-cigarettes at follow-up had also reduced their daily smoking by at least half. So the reduction attributable to e-cigarettes was only 8.2 per cent.
Vaping advocates will chalk this finding up as a tick for harm-reduction, and argue that any cigarette foregone to an e-cigarettes is harm-reducing and therefore a good thing.
This sounds reasonable until we look at the evidence from four cohort studies published since 2006 which reported on whether reducing smoking, as opposed to stopping smoking altogether, reduces the risk of early death.
While there is strong evidence for a causal association between early uptake, amount smoked and duration 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 more than 50 per cent reduce their risk of premature death significantly.
A Scottish study of two cohorts followed from the 1970s to 2010 found no evidence of reduced risk of early death in those who cut their cigarette consumption, 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, which followed 479,156 men for 11 years, 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".
Daily vapers quit less than non-vapers
The third finding deals a massive blow to e-cigarettes' candidacy as the new king of cessation, and to one of the central pillars of the case for e-cigarettes.
For those smokers not using e-cigarettes at the first baseline survey, 12.9% had quit smoking at 12 months, compared with 9.5 per cent non-daily e-cigarette users and just 8.1% daily e-cigarette users. These differences were not statistically significant.
An early randomised controlled trial also found that e-cigarettes were as ineffective as nicotine replacement therapy in cessation at six months follow-up: 92.7 per cent e-cigarette users still smoking compare with 94.2 per cent using nicotine patches. This trial was vigorously pilloried by activist vapers because the e-cigarettes used were "first generation" cigalikes, widely disdained on vaping chat rooms as delivering feeble amounts of nicotine.
This present study seems certain to be shrugged off with the very same arguments, as the most common e-cigarettes used by daily vapers were also cigalikes. In the absence of substantial data about sustained smoking cessation from newer generation "mods" and "tank" systems, this present study provides a window on how most vapers are progressing.
There are many dedicated vapers in the community today who have authentic stories of how they were able to stop smoking with e-cigarettes, often after many failed attempts with nicotine replacement therapy.
But public health policy on e-cigarettes and smoking cessation should not be built on such anecdotes any more than the heartfelt convictions of many drivers who say they're quite safe and incident-free after drinking should challenge the evidence-based data on the risks of alcohol on driving.
Simon Chapman is Professor of Public Health at University of Sydney. Simon Chapman receives funding from the National Health and Medical Research Council for a three year project looking at the natural history of unassisted smoking cessation, the way most ex-smokers have always quit.
This article was originally published on The Conversation.
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