Tobacco RIsk reDuction with E-cigarette Nicotine Therapy among adults with serious mental illness (TRIDENT)

Research question Can people with serious mental illness (SMI) who smoke and who do not want to stop smoking be engaged to reduce harm from and eventually stop smoking with a brief opportunistic intervention and a behavioural support programme? Background Smoking is common in people with SMI and leads to early onset of non-communicable disease.

We can engage 90% of people declining help to stop smoking to switch partially to e-cigarettes with a brief opportunistic intervention.

There is trial evidence that ongoing support for harm reduction increases cessation despite participants initial intentions.

Objectives To develop an intervention to promote, and support persisting use of, an e-cigarette, increasingly switching from smoking to achieve eventual smoking abstinence. Test the brief offer and continued support package in routine mental healthcare to assess feasibility and fidelity. Assess the effectiveness of the intervention in promoting smoking cessation in routine mental healthcare.

Assess the cost-effectiveness of the intervention. Create a package to support implementation in the National Health Service (NHS).

Methods Intervention development will follow the person-based approach and comprise a review of qualitative literature on vaping and discuss the relative importance of these beliefs with our patient panel of people with experience of SMI.

We will adapt a successful brief opportunistic intervention by playing snippets of past consultations to participants with SMI to gauge participants reactions to the intervention and adapt the intervention. We will do likewise with mental health professionals (MHPs) to tailor the intervention to their concerns.

We will use these findings to adapt the cessation-focused SCIMITAR smoking cessation intervention for people with SMI to reduction and, if appropriate, cessation.

Feasibility and fidelity of intervention will be tested in a 3:1 8-week randomised trial with red-amber-green criteria for recruitment, fidelity of brief intervention, follow-up, acceptance of the e-cigarette, and attendance at behavioural support.

Participants waiting to see an MHP will be recruited and randomised to receive a brief opportunistic intervention or no further support. The brief intervention aims to promote switching to vaping if participants decline help to stop smoking. This will comprise an e-cigarette and enrolment on a support programme to promote partial then total switching.

Effectiveness will be tested in a 1:1 randomised trial comprising 958 participants recruited and randomised as in the feasibility trial. The primary outcome is abstinence at three months but prolonged abstinence at 9 months, reduction in smoking to <50% of baseline, and mood changes will be secondary outcomes.

Incremental cost-effectiveness ratios will be assessed using the EQUIPT model to account for the long-term effects of cessation on health and health and social care costs.

Implementation will be supported by an embedded qualitative process assessment to assess conditions needed for implementation and effectiveness.

Timelines for delivery Intervention development 12 months, feasibility 9 months, main trial and process assessment 3-years.

Anticipated Impact and Dissemination Brief opportunistic interventions have high cumulative reach and have been cost saving to the NHS Despite modest effects on cessation could be important for public health.