The authors performed a systematic literature search for data on e-cigarettes' mechanism of action, their emissions, how they are seen by groups of potential users, their efficacy in smoking cessation, and their addiction potential. According to an international survey e-cigarettes were used by younger people, those with higher incomes, and heavier smokers in particular. Among e-cigarette users, 85% reported that they used them to stop smoking.
According to repeat surveys in the U.K., the number of people who were aware of e-cigarettes doubled between 2010 and 2012, and the number of users increased four-fold. An online survey of e-cigarette users found that 74% of those asked had not smoked tobacco for at least several weeks since using e-cigarettes, and 70% reported reduced cigarette cravings. However, there is evidence that people who have never previously smoked also use e-cigarettes.
The rates among Polish and US students, for example, were 3% and 9% respectively. Only two controlled trials show e-cigarettes as having similar effects to nicotine replacement therapies as smoking cessation aids; these effects were almost independent of nicotine content. The authors call for more randomized trials to be conducted.