Smoking cessation for people accessing homeless support centres (SCeTCH): comparing the provision of an e-cigarette versus usual care in a cluster randomised controlled trial in Great Britain

Background Smoking rates are exceptionally high among people experiencing homelessness. We aimed to test the effectiveness of an e-cigarette (EC) intervention designed to help people accessing homeless support services to stop smoking. Methods A two-arm cluster randomised controlled trial. We recruited 32 homeless centres (clusters) across Great Britain. Participants were aged 18 + and known by centre staff to smoke. Randomisation of clusters (1:1; using various block sizes) to EC or usual care (UC) was generated in Stata by the trial statistician, concealed from researchers. Participants in EC clusters received a refillable EC, 4-week supply of e-liquid, and a fact sheet. UC participants received very brief advice on smoking, a support leaflet, and signposting to the stop smoking service. Interventions were delivered by centre staff. The primary outcome was sustained abstinence from smoking from 2 weeks post-baseline through to 24 weeks, verified by carbon monoxide (CO) measurements below 8 ppm. Secondary outcomes included CO-verified 7-day point prevalence abstinence. Analysis was intention-to-treat. Results Between February 22, 2022, and June 22, 2023, 16 centres were randomised to EC (n = 239 participants) and 16 to UC (n = 238 participants). In UC, one participant died, and one withdrew consent. Final sample analysed: n = 239 (EC); n = 236 (UC). Sustained 24-week CO-validated smoking cessation rates were 5/239 (2.1%) with EC vs. 2/236 (0.8%) with UC (aRR: 2.43, 95%CI: 0.51–11.64). Seven-point prevalence abstinence was 15/239 (6.3%) in the EC arm vs. 5/236 (2.1%) in UC (aRR: 2.95, 95%CI: 1.05–8.29). Four adverse events were reported in the EC arm; three deemed EC-related and not serious; one serious and not EC-related. Conclusions EC did not support sustained smoking abstinence for 24 weeks. Seven-day point prevalence abstinence rates suggest that cessation is possible, but more support may be needed to sustain this. Trial registration The trial was preregistered on the ISTCTN registry #18566874. Registration date: 12/10/2021.