Thursday, December 11, 2014

First Meta-Analysis of Existing Studies Concludes that Electronic Cigarettes are Effective for Smoking Cessation

A meta-analysis of the existing studies which examined the effectiveness of electronic cigarettes for smoking cessation has concluded that these products are indeed effective. The study abstract, which was published on the Circulation website, was presented at an American Heart Association conference.

The study concluded as follows: "Six studies were selected, including two randomised controlled trials, two cohort studies and two cross-sectional studies, and included 7,551 participants. Meta-analyses included 1,242 participants on whom complete smoking cessation data was available. Of these, 224 (18%) reported smoking cessation after using nicotine-enriched e-cigarettes for a minimum period of six months. Use of such e-cigarettes was positively associated with smoking cessation with a pooled Effect Size of 0.20 (95% CI 0.11-0.28). Nicotine filled e-cigarettes were more effective in achieving cessation compared to those without nicotine (pooled Risk Ratio 2.29, 95% CI 1.05-4.97). Use of e-cigarettes was also effective in reducing smokers’ daily cigarette consumption."

The Rest of the Story

This meta-analysis reports, as its primary outcome variable, the proportion of smokers using e-cigarettes who quit successfully at six months (or longer). The authors found that 18% of all the smokers using e-cigarettes in the combined studies had quit after six months. This provides preliminary evidence that e-cigarettes do appear to be modestly effective for smoking cessation and that they certainly compare equally or favorably to existing FDA-approved drugs.

In contrast, a previously published meta-analysis of the effectiveness of FDA-approved smoking cessation drugs focuses on the pooled odds ratios. In fact, the study does not even report the absolute cessation rates. Thus, the fact that the study was funded by Pfizer unfortunately appears to be creating a bias in result reporting, as the authors are hiding the key piece of information that readers need to understand whether these drugs are really effective, or whether they are just better than placebo, which has a dismal cessation rate. (None of the authors of the e-cigarette meta-analysis reported any conflicts of interest.)

Remember that a drug can produce an odds ratio of 2, yet represent an 8% cessation rate compared to a 4% cessation rate. Moreover, in these clinical trials, the subjects who received placebo were likely to have known that their medication was inactive and may have suffered a huge initial disappointment which would have resulted in very dismal success rates.

Because this is just an abstract and has not yet been peer-reviewed, its results should be viewed as preliminary. Nevertheless, the conclusion of the study casts doubt on the many anti-smoking groups and advocates who continue to argue that there is no evidence that electronic cigarettes have efficacy in smoking cessation.

Disclosure: I have not received any funding or compensation from the tobacco, electronic cigarette, or pharmaceutical industries. However, I am seeking funding from several electronic cigarette companies to conduct a behavioral study on the effects of electronic cigarettes on smoking behavior.

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