Jim Kling

May 22, 2015

DENVER — People have been blowing smoke about the benefits of e-cigarettes, according to researchers presenting here at the American Thoracic Society (ATS) 2015 International Conference.

Investigators led by Matthew Stanbrook, MD, from the University of Toronto, in Canda, said they suspected that press reports and social media claims that e-cigarettes help smokers were untrue, so they launched a systematic review of the evidence.

"We thought, 'Let's collect all the science there is that's of high quality that can answer the question about safety and efficacy and see what it shows,' " Dr Stanbrook told Medscape Medical News.

They pulled publications from MEDLINE and EMBASE and conducted a full-text review of 297 articles. They selected efficacy studies that enrolled current smokers and that compared e-cigarettes to placebo, active control, or no therapy. That search yielded four studies ― two randomized trials and two uncontrolled before-and-after studies.

"That's one outcome right there," Dr Stanbrook pointed out. There are not much data available on e-cigarettes.

For a safety review, the researchers selected 18 studies that reported any adverse events associated with e-cigarette use.

At 1 month, e-cigarettes significantly improved abstinence among study participants (combined relative risk [RR], 1.71; 95% confidence interval [CI], 1.08 - 2.72). But this effect was not statistically significant at 3 months (RR, 1.95; CI, 0.74 - 5.13) or at 6 months (RR, 1.32; CI, 0.59 - 2.93).

Dry Cough

Adverse effects of e-cigarette use included dry cough, throat irritation, and shortness of breath. The incidence of serious adverse events did not differ between e-cigarettes and placebo.

"At 1 month, e-cigarettes compared to placebo increased the chances of being abstinent from smoking. When you get to 3 or 6 months, that disappears," Dr Stanbrook explained.

He conceded that the studies showed an effect on the amount of cigarettes smoked. "Clinically, that's not necessarily a meaningful outcome, because you don't get the full benefits until you quit smoking for good. But reduction is a validated step on the path to quitting, so it's something," he said.

Dr Stanbrook pointed out that e-cigarettes appeal to patients as a smoking cessation tool because with them, patients can imitate the act of smoking. It satisfies the behavioral component of smoking, such as puffing on a cigarette while drinking morning coffee, which pharmacotherapies and nicotine patches cannot. "The theory is sound, but that doesn't mean it's true; you've still got to prove that it works," he said.

e-Cigarettes don't add a lot therapeutically at this point. Dr Donald Sullivan

The results were disappointing to session moderator Donald Sullivan, MD, from Oregon Health Sciences University, in Portland. Dr Sullivan said he would like to endorse e-cigarettes, provided they were better regulated and there was strong evidence that they worked.

For now, though, he says he cannot recommend them. "Knowing that we have great evidence-based abstinence therapies, I think the e-cigarettes don't add a lot therapeutically at this point," he said.

Dr Sullivan added that his opinion could change if e-cigarettes were regulated. "Once I know what's in them, I can be more of a proponent for them. For me, the priority is smoking cessation at all costs," he said.

Dr Stanbrook and Dr Sullivan report no relevant financial relationships.

American Thoracic Society (ATS) 2015 International Conference: Abstract A3715. Presented May 18, 2015.


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