Too Soon to Say Whether E-Cigarettes Help Smokers Quit: Cochrane Review

What little randomized evidence there is suggests that using electronic cigarettes to aid smoking cessation is effective, albeit with a small effect size, an updated Cochrane review shows. That potential benefit would likely come at little cost in terms of negative effects, as no studies have identified serious adverse events associated with the use of e-cigarettes.

Long-term safety of the devices, which were introduced a decade ago and have since gained in popularity, remains unknown, lead author Jamie Hartmann-Boyce, MA (University of Oxford, England), told TCTMD. Moreover, the current quality of evidence regarding shorter-term outcomes is low because of the small number of studies.

Despite the limited evidence base and the need for more studies, however, it is generally agreed that e-cigarettes are safer than traditional ones, Hartmann-Boyce said.

“You’re not comparing electronic cigarettes to nothing,” she said. “You’re really evaluating them as an alternative to traditional cigarettes, and traditional cigarettes are uniquely deadly. They kill one in two people who use them eventually. So . . . the research community is pretty confident that electronic cigarettes are going to be better in terms of long-term safety than regular cigarettes.”

Suggestion of Benefit

For the current report, published in the Cochrane Database of Systematic Reviews, Hartmann-Boyce and colleagues added 11 new studies to a prior 2014 review. The analysis included 24 studies, including three RCTs.

Two of the randomized trials—with a total of 662 participants—showed that people using e-cigarettes with nicotine were more likely to abstain for at least 6 months compared with those who received placebo e-cigarettes without nicotine (9% vs 4%; RR 2.29; 95% CI 1.05-4.96).

“The effect size (5%) is small, but not unusual given the low level of behavioral support provided,” the authors say.

One other trial compared e-cigarettes with nicotine patches and found no difference in 6-month abstinence rates.

As for safety, none of the studies showed a difference in adverse events between e-cigarettes and placebo. The most common effects were mouth and throat irritation, likely due to “the propylene glycol (a humectant) and nicotine, which has a distinctive hot/peppery taste,” the authors say.

More Answers Coming

Generally, the quality of the evidence regarding the effect of e-cigarettes is low, but there are at least 15 RCTs currently underway, the authors note.

It’s important to have more studies looking at this because the technology of e-cigarettes has evolved to more effectively deliver nicotine, Hartmann-Boyce said.

Until those studies start providing results, it will remain unclear what impact e-cigarettes are having on smoking cessation. Hartmann-Boyce noted that there are proven approaches to helping people quit smoking, particularly dual nicotine replacement therapy—which combines a short-acting product like gum and a long-acting product like the patch—and varenicline (Chantix; Pfizer).

Even with those, however, success rates are still relatively low, opening the door to the possibility of trying e-cigarettes, she said.

“My personal opinion would be that as a general practitioner, it would be useful to have that conversation about electronic cigarettes,” she said, noting that there are misperceptions about how risky e-cigarettes are, with some viewing them as comparable to or worse than traditional cigarettes.

“Everything we know suggests that’s not the case, so I think it’s definitely important for physicians to provide accurate information on their safety profile in relation to regular cigarettes,” she said.

Todd Neale is the Associate News Editor for TCTMD and a Senior Medical Journalist. He got his start in journalism at …

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  • Hartmann-Boyce J, McRobbie H, Bullen C, et al. Electronic cigarettes for smoking cessation. Cochrane Database Syst Rev. 2016;Epub ahead of print.

  • Hartmann-Boyce reports being funded by the National Institute of Health Research School for Primary Care Research.