Cohort study of electronic cigarette use: effectiveness and safety at 24 months

Despite their potential public health relevance, the current evidence on the safety and efficacy/ effectiveness of e-cigarettes is scarce, and long-term data are urgently needed. The published prospective evidence on the efficacy/effectiveness for healthy participants consists of 2 randomised trials, single-arm small trials and 11 observational studies. However, these studies mostly included users of both tobacco and e-cigarettes followed for ≤12 months, used various assessment methods, and did not directly compare e-cigarette users and tobacco smokers. Moreover, the entire evidence on e-cigarette safety—at 6 months —is limited to 122 healthy participants, most of whom were also smoking tobacco for most of the follow-up. We previously reported the 12-month follow-up results of our 5-year study aimed at evaluating the long-term effects of e-cigarette use. We report the results of the 24-month follow-up, and include hospital discharge data.