Reacción a "Clinical trial compares efficacy of e-cigarettes and varenicline for smoking cessation"

This is a randomised clinical trial, in principle well conducted, comparing three treatment groups (an e-cigarette (EC) with nicotine group, a varenicline plus EC without nicotine group, and a placebo control group) for smoking cessation in heavy smokers (heavy and long term smokers) interested in quitting and includes intensive motivational support. Results show that both EC with nicotine and varenicline increase cessation compared to EC without nicotine. At one-year follow-up, 28% of smokers using nicotine-containing ECs remained abstinent, as did 37.9% of those using varenicline and 19.9% of the control group.  

The results are relevant and a plain reading indicates that varenicline and EC with nicotine are equally effective in smoking cessation. However, the clinical relevance of the efficacy of varenicline is much higher (18 percentage points) than that of EC with nicotine (8.1 percentage points), beyond statistical significance which is most likely not reached due to a methodological problem. The trial seems designed to test the superiority in efficacy of nicotine-containing EC or varenicline over placebo, not to compare the equivalence of treatment with nicotine-containing EC and varenicline. For this type of equivalence comparison, a larger sample size is needed. And these details are not included in the main article, and the appendices and supplementary materials could not be consulted. 

Although the results are promising for the use of nicotine-containing ECs in smoking cessation consultation, even though they have lower efficacy than varenicline, the trial has other limitations. Firstly, the article assumes that ECs are much safer than conventional cigarettes, so the authors do not consider continued use of ECs as a complication. A recently published meta-analysis shows that, for several outcomes, ECs have disease risks indistinguishable from conventional cigarettes, and for others, although lower, the risks remain substantial. The second problem lies in the nature of the trial participants. It is well known that trial participants differ in important respects from non-participants. Smokers who participate in trials attended by smoking cessation clinics are a self-selected minority of smokers who may differ in important respects from smokers who do not seek professional assistance. Therefore, these results may not be generalisable to all smokers who quit, as 65-75% of ex-smokers have quit without professional help.  

The article does not provide sufficient evidence to include EC as a smoking cessation therapy in routine health care until it is approved as a smoking cessation therapy by the European and Spanish competent authorities. To our knowledge, no CE companies (mostly part of the tobacco industry) have presented their products as therapeutic interventions.