Tailored interventions to assist smokers to stop smoking using e-cigarettes (TASSE): Study protocol [version 3]

Background: T here is increasing evidence that e-cigarettes (EC) are an effective smoking cessation aid when combined with behavioural support. T here is further evidence for digital tailored interventions as cost effective approaches that can increase smoking cessation rates. Experimental work also suggests the addition of a ‘nicotine fact sheet’ can improve smokers’ risk perceptions related to EC. However, multifaceted approaches to deliver ‘tailored advice’ for smoking cessation combining various key evidenced based components are lacking. T he aim of this study is to use a Multiphase Optimisation Strategy (MOST ) to determine which of five, or a combination thereof, EC-orientated intervention components is associated with self-reported cessation over the previous 4-weeks at 12-week follow-up. Methods/Design: T his online study will utilise a 2x2x2x2x2 factorial design resulting in 32 experimental conditions. T he five intervention components will be: 1: tailored advice on EC device; 2: tailored advice on e-liquid nicotine strength; 3: tailored advice on eliquid flavour; 4: e-cigarette written information; 5: text message support. A sample of N=1184 adult, UK resident smokers will be randomly allocated to one of the 32 conditions, which will be permutations of the 5 components (counter-balanced). T he primary outcome is 4 weeks of self-reported complete abstinence at 12 weeks post randomisation. Secondary outcomes are 7-day point prevalence, 50% reduction in baseline cigarettes smoked per day, time to switch and adherence to recommendation. T he primary analysis will be by intent-to-treat with the assumption that missing equals smoking. Logistic regression will be used to model the five main effects and the ten 2x2 interactions. A number of secondary analyses will also be conducted including models adjusting for demographic and smoking indices and including only those who received the intervention. Discussion: T o date, components that assist quitting by use of EC or other aids have largely been studied in isolation. T his study presents the first attempt to combine evidenced based interventions, using the MOST method, to test which components are associated with quitting. T he findings will be used to inform which components to include and their estimated effect sizes for a definitive randomised controlled trial (RCT ) to examine the efficacy of the intervention compared with usual care (own choice and no support)