The harmful health effects of children’s exposure to secondhand smoke (SHS) are well established. Most SHS exposure now occurs in the home, in low-income households. Previous research suggests that using nicotine replacement therapy (NRT) in the home can help with temporary smoking abstinence and could reduce smoking indoors. This pilot randomised controlled trial tests the feasibility of providing parents, carers and relatives with posted-to-home nicotine replacement therapy alongside fortnightly telephone support to reduce children’s exposure to SHS.

100 participants are being recruited through existing National Health Service (NHS) Lanarkshire initiatives and social media. Parents/carers who are at least 18 years old, smoke in the home and care for one or more children aged 0–16 years are eligible to take part. Participants are randomised to either the intervention (Group A) or control (Group B) arm. Group A receives NRT posted to their home for 12 weeks free of charge, alongside fortnightly telephone calls and materials to support them in reducing children’s exposure to SHS. Group B is signposted to the Scottish Government’s ‘Take it Right Outside’ website which provides interactive advice on creating a smoke-free home. To quantify the child’s exposure to SHS, participants instal an air quality monitor to measure fine particulate matter (PM_2.5) concentrations in their living room for 7 days at baseline and 12-week follow-up and/or collect and post saliva samples from their youngest child (age 5 or over) for cotinine analysis. Qualitative interviews explore intervention experience, NRT use and adherence and changes to home-smoking behaviours/smoking-related expenditure. Descriptive data analyses will be performed to address the feasibility of recruitment, randomisation, retention and adherence, data collection and intervention delivery. Analysis will also include pre/post changes (paired t-test) in both child’s salivary cotinine and PM_2.5 levels to provide preliminary data on intervention effectiveness and difference between the intervention and control arms of the study. Health economics and resource use data will be collected and assessed for completeness, to test the process of data collection and estimate mean cost of both study arms.

NHS ethical approval has been obtained by the West of Scotland Research Ethics Service (15 December 2023, ref 23/WS/0153; 13 December 2024, ref AM01). The findings will be disseminated to participants, funders, NHS Lanarkshire and other health services, and in peer-reviewed journals and academic conferences. Findings will inform new approaches that are timely and important, providing valuable evidence to help reduce children’s exposure to SHS in the home in Scotland and elsewhere.

ISRCTN79307718.

Around 80% of the world’s smokers live in lower-middle income countries and smoking rates in China, Philippines and Indonesia are very high. Evidence suggests that most people begin smoking or become habitual smokers before reaching adulthood. This highlights the need for a smoking prevention intervention focused on young people. ASSIST (A Stop Smoking In Schools Trial) is a ‘peer-led’, school-based smoking prevention intervention, shown to be effective in the UK. The aim of the study is to assess the feasibility of conducting a full-scale effectiveness evaluation of an adapted version of the ASSIST intervention in China, Indonesia or the Philippines. However, due to issues with obtaining relevant approvals, China was removed from the trial with the approval of the funder and Trial Steering Committee, and the study will only be completed in Indonesia and the Philippines.

A feasibility mixed-methods cluster randomised controlled trial in 10 schools (six intervention, four control) in each of the two countries. Participants will be students aged c13–14 in mainstream (‘lower secondary’) schools. In addition to their usual education on smoking, intervention schools will receive the ASSIST intervention which is based on ‘diffusion of innovation’ theory, with new norms and behaviours promoted through: (1) peer modelling by locally influential individuals; and (2) information disseminated by them through their social networks. Control schools will continue with their usual education around smoking prevention.

The key outcome of the study is whether prespecified progression criteria relating to recruitment, retention, acceptability and feasibility have been met in order to progress to a larger cluster randomised controlled effectiveness trial in one or more of the countries. A mixed-methods process evaluation will assess acceptability, feasibility and fidelity of intervention delivery, exposure to and reach of the intervention. The feasibility of trial processes including outcome measurement will be assessed. An economic evaluation will estimate the costs of the ASSIST intervention. Statistical analyses will focus on feasibility criteria, and qualitative data will be analysed using a framework approach. Outcomes assessed will include self-reported smoking behaviour (own and that of friends and family); vaping and other forms of nicotine use; smoking-related attitudes and knowledge; smoking norms; self-esteem; self-efficacy; (all at baseline and 7 month follow-up) and exhaled carbon monoxide concentration (at follow-up only).

The trial has been approved by the University of Glasgow College of Medical, Veterinary and Life Sciences (MVLS) Ethics Committee (ref: 200210204), the De La Salle University Research Ethics Review Committee (ref: 2023-012C) and the Medical and Health Research Ethics Committee (MHREC); Faculty of Medicine, Public Health and Nursing; Universitas Gadjah Mada (ref: KE/FK/1205/EC/2022). The trial is sponsored by the University of Glasgow (Head of Research Regulation and Compliance—debra.stuart@glasgow.ac.uk). The sponsor will not have input in data collection, management, analysis and interpretation; write up and submissions for publication.

The study findings will be disseminated through peer-reviewed publications in expert journals and conference presentations and targeted communications to schools, policymakers and the public.

ISRCTN99140476.