Use of nicotine replacement therapy to create a smoke-free home: study protocol for a pilot randomised controlled trial of a smoke-free home intervention in Scotland.

INTRODUCTION

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.

METHODS AND ANALYSIS

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) 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 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.

ETHICS AND DISSEMINATION

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.

TRAIL REGISTRATION NUMBER

ISRCTN79307718.