[Intended and unintended effects of e-cigarettes in clinical studies: a plea for (more) transparency].

E-cigarettes are used in clinical trials to facilitate smoking cessation. Due to the health risks associated with the use of e-cigarettes, the results of clinical trials should be fully reported, including continued exclusive use and dual use of tobacco and e-cigarettes. Nicotine cessation outcomes should be reported as the primary endpoint as well as the analysis of tobacco cessation alone. As there is currently no robust evidence that reducing cigarette consumption provides substantial health benefits, cigarette consumption reduction should not be used as a health outcome in clinical trials. Continued nicotine dependence should be included as an "adverse event" in the reporting of trial results.