Introduction Thousands of patients with mental illness are admitted to acute adult mental health wards every year in England, where local guidance recommends that all mental health settings be entirely smokefree. Mental health trusts presently invest substantial effort and resources to implement smokefree policies and to deliver tobacco dependence treatment to patients. Providing adequate support can help smokers remain abstinent or quit smoking during their smokefree inpatient stay and beyond. At present, little is known about how best to support patients to prevent their return to pre-admission smoking behaviours after discharge from a smokefree mental health inpatient stay. We have developed an intervention which includes targeted resources to support smoking-related behaviour change in patients following discharge from a smoke-free mental health setting. The aim of this trial is to determine the feasibility of a large-scale clinical trial to test the effectiveness and cost-effectiveness of the SCEPTRE intervention, compared with usual care. Methods and Analysis This feasibility study will be an individually randomised, controlled trial in eight National Health Service (NHS) mental health trusts recruiting adults (18 years and older) admitted to an acute adult mental health inpatient setting who are tobacco smokers on admission, or at any point during their inpatient stay. Consenting participants will be randomised to receive a 12-week intervention consisting of components aimed at promoting or maintaining positive smoking-related behaviour change following discharge from a smoke-free mental health inpatient setting or usual care. Data will be collected at baseline, 3-months and a second timepoint between 4-6 months post-randomisation. With 64 participants (32 in each group) the trial will allow a participation rate of 15% and completion rate of 80% to be estimated within a 95% confidence interval of +/-3% and +/-10% respectively. The analysis will be descriptive and follow a prespecified plan. Ethics and Dissemination Ethics approval was obtained from the North West - Greater Manchester West Research Ethics Committee. We will share results widely through local, national and international academic, clinical and Patient and Public Involvement (PPI) networks. The results will be disseminated through conference presentations, peer-reviewed journals and will be published on the trial website: https://sceptreresearch.com/.

LS has received honoraria for talks, an unrestricted research grant and travel expenses to attend meetings and workshops from Pfizer and an honorarium to sit on advisory panel from Johnson & Johnson, both pharmaceutical companies that make smoking cessation products. He has acted as paid reviewer for grant awarding bodies and as a paid consultant for health care companies. Other research has been funded by the Department of Health, UKRI, a community-interested company (National Centre for Smoking Cessation) and charitable sources (Cancer Research UK, Yorkshire Cancer Research). He has never received personal fees or research funding of any kind from alcohol, electronic cigarette or tobacco companies. All other authors declare no conflicts of interest.

ISRCTN77855199

The SCEPTRE Feasibility Trial is funded by Programme Grants for Applied Research (NIHR200607). The sponsor is the Sheffield Health and Social Care NHS Foundation Trust. Catherine Hewitt, Simon Gilbody and Tim Coleman are NIHR Senior Investigators. The trial will be monitored and audited in accordance with the sponsors procedures. The sponsor will play no role in the study design, collection, management, analysis, and interpretation of data; writing of the report; and the decision to submit the report for publication. PPW, LH, ES, and ER are supported by the NIHR Yorkshire and Humber Applied Research Collaboration.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The protocol (Version 1.0_05.09.2023) for this study and the informed consent form (see online supplemental appendix 2) were approved by the North West - Greater Manchester West Research Ethics Committee (REC) (23/NW/0312). The Investigators will ensure that this study is conducted in full conformity with current regulations, the current revision of the Declaration of Helsinki, and with the principles of GCP. We will adhere to the UK Framework for Health and Social Care Research [22, 39]. The programme manager/CI will obtain approval for all amendments.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

All data produced in the present study are available upon reasonable request to the authors