Thursday, December 18, 2014

Cochrane Review Concludes that Electronic Cigarettes Appear to Be Effective for Smoking Cessation and Reduction, Although Further Research is Necessary

The first Cochrane review of the effectiveness of electronic cigarettes has concluded that there is enough evidence to declare that these products are effective for smoking cessation and reduction.

(See: McRobbie H, Bullen C, Hartmann-Boyce J, Hajek P. Electronic cigarettes for smoking cessation and reduction. The Cochrane Library. Published online on December 17, 2014. DOI: 10.1002/14651858.CD010216.pub2.)

The authors describe their study inclusion criteria as follows: "We included randomized controlled trials (RCTs) in which current smokers (motivated or unmotivated to quit) were randomized to EC or a control condition, and which measured abstinence rates or changes in cigarette consumption at six months or longer. As the field of EC research is new, we also included cohort follow-up studies with at least six months follow-up. We included randomized cross-over trials and cohort follow-up studies that included at least one week of EC use for assessment of adverse events."

The results of the study were as follows: "Participants using an EC were more likely to have abstained from smoking for at least six months compared with participants using placebo EC (RR 2.29, 95% CI 1.05 to 4.96; placebo 4% versus EC 9%; 2 studies; GRADE: low). The one study that compared EC to nicotine patch found no significant difference in six-month abstinence rates, but the confidence intervals do not rule out a clinically important difference (RR 1.26, 95% CI: 0.68 to 2.34; GRADE: very low). A higher number of people were able to reduce cigarette consumption by at least half with ECs compared with placebo ECs (RR 1.31, 95% CI 1.02 to 1.68, 2 studies; placebo: 27% versus EC: 36%; GRADE: low) and compared with patch (RR 1.41, 95% CI 1.20 to 1.67, 1 study; patch: 44% versus EC: 61%; GRADE: very low). Unlike smoking cessation outcomes, reduction results were not biochemically verified. None of the RCTs or cohort studies reported any serious adverse events (SAEs) that were considered to be plausibly related to EC use."

The authors conclude: "There is evidence from two trials that ECs help smokers to stop smoking long-term compared with placebo ECs. However, the small number of trials, low event rates and wide confidence intervals around the estimates mean that our confidence in the result is rated 'low' by GRADE standards. The lack of difference between the effect of ECs compared with nicotine patches found in one trial is uncertain for similar reasons. ECs appear to help smokers unable to stop smoking altogether to reduce their cigarette consumption when compared with placebo ECs and nicotine patches, but the above limitations also affect certainty in this finding. In addition, lack of biochemical assessment of the actual reduction in smoke intake further limits this evidence. No evidence emerged that short-term EC use is associated with health risk."

The Rest of the Story

There is clearly a need for further research in this area, and the authors make it clear that they have low confidence in their conclusions because of the limited evidence. However, it does appear that at the current time, there is evidence that electronic cigarettes can be useful for smoking cessation and reduction and that they are probably at least as effective as other FDA-approved therapies. In addition, there is no evidence that these products cause any serious adverse side effects, at least in terms of short-term use.

These conclusions refute the statements being made by a number of tobacco control researchers and advocates that electronic cigarettes actually inhibit smoking cessation. And they also refute statements by some health agencies that there is no evidence that electronic cigarettes have any usefulness for smoking cessation.

There is an urgent need for a high-quality clinical trial of electronic cigarettes in the United States, especially since more conclusive information is necessary to inform the FDA as it prepares and implements regulations. I developed a protocol for such a study, but was unable to secure funding from electronic cigarette companies to conduct the study. Hopefully, someone will be able to secure funding. I am happy to share my protocol with any researchers who are interested in potentially conducting such a study.

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