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

Background: There is increasing evidence that e-cigarettes (EC) are an effective smoking cessation aid when combined with behavioural support. There 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. The 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: This online study will utilise a 2x2x2x2x2 factorial design resulting in 32 experimental conditions. The five intervention components will be: 1: tailored advice on EC device; 2: tailored advice on e-liquid nicotine strength; 3: tailored advice on e-liquid 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). The 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. The 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: To date, components that assist quitting by use of EC or other aids have largely been studied in isolation. This study presents the first attempt to combine evidenced based interventions, using the MOST method, to test which components are associated with quitting. The 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).