E-cigarette support for smoking cessation: Identifying the effectiveness of intervention components in an online randomised optimisation trial

This is an online study of 1214 UK smokers which aimed to determine which combination(s) of five intervention components can help smokers to stop smoking by using an e-cigarette. A balanced five-factor randomised factorial design was used, guided by the Multiphase Optimisation Strategy (MOST). The five intervention components were: i) tailored advice on which e-cigarette device to purchase; ii) tailored advice on which e-liquid nicotine strength to purchase; iii) tailored advice on which flavour to purchase; iv) brief information on relative harms of e-cigarettes vs smoking; v) text message support. Participants completed a baseline survey online and were then randomised to either receive or not receive each intervention component (resulting in 32 possible combinations). Tailored advice on device, nicotine strength and flavour were based on responses to baseline questions and were displayed at the end of the survey (for participants randomised to receive that condition). Follow up data was collected via a second online survey after 12 weeks to collect information on abstinence rates and adherence to intervention components. Logistic regressions were used to model the main effects and two-way interactions on the primary outcome (4-weeks abstinence) and secondary outcomes (7-day point prevalence and ≥50% smoking reduction). The full dataset and syntax (as SPSS files) are available. Link to protocol: https://www.qeios.com/read/9RDLJA.3 Link to trial registry: https://www.isrctn.com/ISRCTN54776958 Link to published paper: To follow (currently under review with Addiction