1 Bryant M, et al. BMJ Open 2024;14:e081861. doi:10.1136/bmjopen-2023-081861 Open access Effectiveness and cost-effectiveness of a sustainable obesity prevention programme for preschool children delivered at scale ‘HENRY’ (Health, Exercise, Nutrition for the Really Young): protocol for the HENRY III cluster randomised controlled trial Maria Bryant , 1,2 Wendy Burton, 2 Michelle Collinson, 3 Adam Martin, 4 Bethan Copsey , 3 Dawn Groves-Williams , 3 Alexis Foster , 5 Thomas A Willis, 6 Philip Garnett, 7 Alicia O'Cathain 5 To cite: Bryant M, Burton W, Collinson M, et al. Effectiveness and cost-effectiveness of a sustainable obesity prevention programme for preschool children delivered at scale ‘HENRY’ (Health, Exercise, Nutrition for the Really Young): protocol for the HENRY III cluster randomised controlled trial. BMJ Open 2024;14:e081861. doi:10.1136/ bmjopen-2023-081861 ► Prepublication history and additional supplemental material for this paper are available online. To view these files, please visit the journal online (https://doi.org/10.1136/ bmjopen-2023-081861). Received 09 November 2023 Accepted 04 March 2024 For numbered affiliations see end of article. Correspondence to Professor Maria Bryant; maria.bryant@york.ac.uk Protocol © Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ. ABSTRACT Introduction One-fifth of children start school already overweight or living with obesity, with rates disproportionately impacting those living in the most deprived areas. Social, environmental and biological factors contribute to excess weight gain and programmes delivered in early years settings aim to support families to navigate these in order to prevent obesity. One of these programmes (Health, Exercise and Nutrition for the Really Young, HENRY) has been delivered in UK community venues (hereon named ‘centres’) in high deprivation areas since 2008 and aims to help families to provide a healthy start for their preschool children. We aim to establish the effectiveness and cost-effectiveness of HENRY, including its potential role from a wider systems perspective. Methods and analysis This is a multicentre, open- labelled, two-group, prospective, cluster randomised controlled trial, with cost-effectiveness analysis, systems-based process evaluation and internal pilot. Primary analysis will compare body mass index (BMI) z-score at 12 months in children (n=984) whose parents have attended HENRY to those who have not attended. Secondary outcomes include parent and staff BMI and waist circumference, parenting efficacy, feeding, eating habits, quality of life, resource use and medium term (3 years) BMI z-scores (child and siblings). 82 centres in ~14 local authority areas will be randomised (1:1) to receive HENRY or continue with standard practice. Intention-to- treat analysis will compare outcomes using mixed effects linear regression. Economic evaluation will estimate a within-trial calculation of cost-per unit change in BMI z- score and longer-term trajectories to determine lifelong cost savings (long-term outcomes). A systems process evaluation will explore whether (and how) implementation of HENRY impacts (and is impacted by) the early years obesity system. An established parent advisory group will support delivery and dissemination. Ethics and dissemination Ethical approval has been granted by the University of York, Health Sciences’ Research Governance Committee (HSRGC/2022/537/E). Dissemination includes policy reports, community resources, social media and academic outputs. Trial registration number ISRCTN16529380. INTRODUCTION Reducing the prevalence of childhood obesity among people living in deprived areas is a public policy priority. Approx- imately one- third of children (27.7% on average and up to 34.5% in higher STRENGTHS AND LIMITATIONS OF THIS STUDY ⇒ The Health, Exercise and Nutrition for the Really Young (HENRY) III trial provides an opportunity to examine the effectiveness and cost-effectiveness of an intervention that has been publicly funded and delivered at scale for more than 10 years, including short-term, medium-term and long-term outcomes. ⇒ Our systems-based process evaluation will explore the role that community-based obesity prevention interventions play within the wider system, based on the understanding that factors that influence obesity are complex and multifaceted. ⇒ The HENRY III trial has been designed following a successful feasibility study, in collaboration with lo- cal and national government partners, members of the public and a multidisciplinary trial team. ⇒ The trial’s success is dependent on recruitment of local authority areas, where additional funding will be required to commission the intervention. ⇒ A mitigation strategy has been developed to reduce the risk of selection bias inherent in cluster designs. on July 24, 2024 by guest. 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