A novel population data-driven approach to quantifying feasibility of recruitment during the study planning stage: lessons learnt from an e-cigarette pilot study

Long-term effects of e-cigarette use remain insufficiently characterised to inform regulatory decisions.1 To contribute to this evidence gap, we conducted a pilot e-cigarette study nested within the Miami Heart study, a prospective cohort of English-speaking adults, aged 40–65 and free of known cardiovascular disease. A total of 2459 participants were enrolled in the parent cohort between 2015 and 2018.2 Using this cohort infrastructure, we aimed to recruit 30 sole e-cigarette users using diverse strategies including vape shops, employer networks, existing cohort members and digital outreach.