- Wednesday, 26 June 2013 15:58
Efficacy of e-cigarette as a tobacco substitute-a randomized study
In this interesting study published in PLoS One, the effect of electronic cigarette use on smoking reduction and cessation was tested. It is a proper, randomized, double-blind but not placebo control (for reasons I will explain later) study.
Researchers recruited smokers who were not willing to quit, and thus the results certainly underestimate the true potential of e-cigarettes and cannot be compared to any other smoking cessation study in which participants are highly-motivated to quit. Moreover, no psychological support was provided, which further supports that smoking reduction rate could be even higher. I believe the authors deliberately did that, because they wanted to make a study representing real-life situations and not an “idealistic” approach that would not be applicable to daily practice.
The efficacy or e-cigarette on smoking reduction and abstinence was less than expected due to the device used. A 90mAh battery is certainly insufficient for this purpose and I am sure a lot of participants would find this frustrating, especially since only two batteries were provided to each participant. Finally, the limit of 4 cartridges per day was probably low and certainly not enough for most smokers, especially during the initial period.
The authors very cleverly realised that there is no placebo in electronic cigarette use. The reason is that the electronic cigarette is not just a device to deliver nicotine to the user. It mimics smoking and provides behavioural, visual and sensory stimulation, even when no nicotine is used. So, I absolutely agree and support their approach. Had they considered non-nicotine cartridges as placebo, the study would have shown no effect of e-cigarette in reducing or substituting smoking; but this is not the case. I would object however to the classification of e-cigarettes cartridges according to their total nicotine content. I find this inappropriate and I would classify them according to their nicotine concentration (which was 22.7mg/ml in one group and 17.1mg/ml in the other group).
A very important conclusion of the study was that those who quit smoking early in the trial were more likely to remain smoke-free after 1 year. This means that e-cigarette use should be initiated with the goal of completely substituting smoking. Maintaining tobacco cigarette use for a long time means that these people are highly likely to never quit and relapse to previous cigarette consumption. Another important finding was the safety of e-cigarette use. No adverse effects were observed, and health benefits were reported by users compared to the period when they were smoking.
Overall, 11% of participants managed to quit smoking at 1 year using nicotine-containing e-cigarette, while 4% also quit with zero-nicotine cartridges.
Some scientists criticised the study because of the high percent of participants lost to follow-up. Overall, 39% of participants were lost to follow up. This is a common phenomenon for smoking-cessation studies. Researchers analysed the results on an intention-to-treat basis, which means that they considered all people lost to follow-up as failures. This means that their analysis was performed according to the most pessimistic scenario; therefore, critics should read the paper more carefully before trying to underestimate the findings.
Overall, this is an important study. Results are not impressive, but that was expected when you use an old device which is inefficient (and is not currently produced). The major conclusion is that the potential of e-cigarettes to reduce or completely substitute smoking is a reality. What we already know from experience has been proven by a clinical trial. Studies should now be focused more on safety.
*A study comparing e-cigarettes with nicotine patch is expected to be published in September this year.