Effects of e-cigarettes vs usual care for smoking cessation when offered at homeless centres: The SCeTCH cRCT

Background: Smoking rates are up to four times higher among people experiencing homelessness compared to the housed population and how to support them to quit is unclear. Objective(s): To test the effectiveness and cost-effectiveness of providing e-cigarettes (EC) to people accessing homeless support services to stop smoking. To explore implementation fidelity, contextual influences and mechanisms of change. Trial Design: A two-arm cluster randomised controlled trial with cost-effectiveness and mixed-methods process evaluation. Methods: Setting and participants: 32 homeless centres (clusters) across Great Britain. Participants were aged 18+ and known by centre staff to smoke. Sixteen staff and 31 participants in EC centres completed qualitative interviews. Interventions: Clusters were randomised (1:1) to EC or usual care (UC) prior to staff training. EC participants received a refillable EC, 4-weeks’ supply of e-liquid and a fact sheet. UC participants received Very Brief Advice on smoking, a support leaflet and signposting to Stop Smoking Service. Main outcome measures: Primary outcome: carbon-monoxide (CO) verified sustained smoking abstinence from 2-weeks post-baseline to 24-weeks. Secondary outcomes: CO-verified 7-day point prevalence (PP) abstinence, <50% smoking reduction, intervention costs, QALYs, implementation fidelity and mechanisms of change. Results: Sixteen 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-verified 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). 7- day PP abstinence at 24-weeks was 15/239 (6.3%) with EC vs. 5/236 (2.1%) with UC (aRR:2.95, 95%CI:1.05-8.29). Smoking reduction (<50%) at 24 weeks was 83/239 (34.7%) with EC vs 40/236 (17%) with UC (aRR:2.02, 95%CI:1.44-2.84). Four adverse events were reported in the EC arm; three EC-related and not serious; one serious and not EC-related. Mean per participant intervention costs were £92 (Standard Error (SE) £0) for EC and £50 (SE £0) for UC. Mean total costs were £3,859 (SE £441) versus £2,716 (SE £386) in EC and UC group respectively. QALYs were estimated at 0.303 (SE 0.008) for EC and 0.295 (SE 0.010) for UC. From NHS and personal social service perspective, the EC arm was £1,267 (95% CI £219 to £2,347) more costly and yielded 0.007 (95% CI -0.016 to 0.033) more QALYs, than UC. The ICER was £181,000 per QALY gain. EC intervention was delivered with high fidelity with no variation by centre size or location although staff capacity and resourcing were barriers to implementation. Quit enablers included high capability to use EC, support from friends/family, and increased motivation following smoking reduction. Barriers included lack of satisfaction with EC compared with smoking, a strong smoking culture at centres, and staff deprioritising tobacco-related harm. Limitations: Low quit rates resulted in insufficient power to detect an effect on the primary effectiveness and cost-effectiveness outcomes, leading to uncertainty. Conclusions and Future work: EC showed no effectiveness for 24-week sustained smoking abstinence. 7-day PP abstinence and smoking reduction was possible, and staff can support the intervention. Longer term and potentially different types of support and systems-change are needed to support sustained abstinence.