Evidence that electronic cigarettes are effective for smoking cessation long-term is lacking

"While e-cigarettes have been shown to significantly improve abstinence at 1 month compared with placebo, no such evidence is available supporting their effectiveness for longer periods," said lead author Riyad al-Lehebi, MBBS, of the University of Toronto. "Until such data are available, there are a number of other smoking cessation aids available that have a more robust evidence base supporting their efficacy and safety."

The meta-analysis included four studies of the efficacy and safety of e-cigarettes for promoting smoking cessation in 1011 patients and an additional 18 studies of the safety of e-cigarettes reporting adverse effects that occurred in 1212 patients.

At 1 month, e-cigarettes significantly improved the prevalence of abstinence among study subjects, but this effect was no longer observed at 3- or 6-month follow-ups. In one study, no significant difference in 6-month abstinence rates were observed between e-cigarettes and placebo or between e-cigarettes and the nicotine patch.

Adverse effects of e-cigarette use noted in the studies included dry cough, throat irritation, and shortness of breath. The incidence of serious adverse events did not differ between e-cigarettes and placebo e-cigarettes, but e-cigarette use was associated with a higher rate of adverse effects than the nicotine patch.

"Although e-cigarettes are widely promoted and used as a smoking cessation tool, we found no data supporting their long-term efficacy and safety," said al-Lehebi. "Given the potential health risks of using these unproven and unregulated devices, individuals seeking help with smoking cessation should consider other more well-established options until more research is performed."