Effects of e-cigarettes vs usual care for smoking cessation when offered at homeless centres: A cluster randomised controlled trial

Adult smoking rates in the UK are at a historic low, at 14.1%. However, this masks considerable inequalities. Prevalence amongst adults who are homeless, is four times higher than the national average. Homeless smokers make fewer quit attempts, are less likely to stop smoking but show desire to quit. The harms of tobacco smoking are exacerbated in this population because of concurrent smoking of illicit substances which compromise lung function. There is therefore an urgent need to explore the efficacy of novel approaches for smoking cessation in one of the most vulnerable and hard to treat groups in society. E-cigarettes (EC) are the most common method used in a quit attempt in the UK and evidence for their efficacy is accumulating. However, initial start-up costs may deter those on lower incomes from buying one. Our feasibility study (NIHR ref.17-55-29) in 4 homeless centres in England and Scotland in 2019 demonstrated that providing a free EC starter kit was acceptable to staff and clients. We met our overall minimum recruitment and retention targets and collected most of the information needed for economic evaluation. We now propose a full trial which aims to determine the efficacy and cost-effectiveness of providing free EC starter kits to smokers accessing homeless centres compared with usual care (UC). The trial will take place in 32 homeless centres (who will serve as clusters) across GB, allocated either to an EC or UC arm. Allocation will be stratified by region (n=5: Scotland, Wales, London, East England, and South East) using stratified permuted blocks to ensure balance. 480 participants (15 smokers in each centre) will complete questionnaires about general health and smoking behaviour and provide a breath carbon monoxide (CO) sample at baseline. Those in the EC arm (N=240) will be provided with an EC starter kit, 4-weeks supply of e-liquids and support from trained centre staff to use them. Follow up assessments including smoking behaviour, quit rates, CO levels, health-related quality of life, health-care service utilisation will be conducted at 4, 12 and 24 weeks. Participants in the UC group (N=240) will be provided with information on smoking cessation and how to access their local stop smoking service and will be followed up at the same time points. An inbuilt pilot study with 120 participants (8 centres) will monitor recruitment with green/amber/red stop/go criteria. An embedded mixed methods process evaluation using both quantitative (e.g. questionnaires) and qualitative (e.g. interviews) approaches will explore treatment context, fidelity of implementation, mechanisms of change and sustainability. Mechanisms of change and context will be explored through in-depth qualitative interviews with 32 participants (weeks 12-24) and 16 staff members (weeks 4-8) in 8 centres (4 England, 2 Wales, 2 Scotland) in the EC arm. An economic evaluation (an incremental cost-effectiveness of the EC intervention over and above UC) will also be conducted. We will share our findings with the participants and the homeless centres involved and will make our findings available online and via social media and press releases. Pathways to implementation across homeless centres in GB will be explored through workshops with key decision makers in each country