Evaluation of a sustainable obesity prevention programme delivered at scale ‘HENRY’: Effectiveness, cost-effectiveness and its role in obesity prevention within the wider complex system

Background: Childhood obesity disproportionately impacts those living in the highest levels of deprivation. COVID has had a profound effect on rates, where almost a third of children start school with overweight/obesity (~25% pre-COVID). The most widely funded community obesity prevention intervention, HENRY, has been delivered at scale in areas of high deprivation since 2008.

Aim: Following a successful feasibility study, we aim to establish the effectiveness and cost-effectiveness of an obesity prevention programme delivered at scale, including its potential role from a wider systems perspective.

Research questions:? What is the effectiveness and cost-effectiveness of HENRY in terms of reducing the risk of obesity in children??Does HENRY influence obesity rates in parents, siblings and centre staff??What does the obesity system in which HENRY is positioned look like? What role does HENRY play in childhood obesity prevention within the wider system?

Methods: Design: Multi-centre, open-labelled, two group, prospective, cluster RCT, with cost-effectiveness analysis, systems based process evaluation and internal pilot.

Randomisation: Centres within local authorities will be randomised to receive HENRY or continue with standard practice (1:1) stratified by centre size, area level ethnicity and area level deprivation. Setting: Local authority children’s centres/other community venues.

Intervention: Centre practitioners receive core HENRY training to influence centre environment (culture, policy, practice) to promote positive behaviours among workforce and families. A proportion of these are trained to deliver an 8-week HENRY programme to parents attending centres. Parents gain skills and knowledge to provide a healthy start for their child.

Comparator: Staff within control centres will not receive HENRY training and will continue to deliver usual programmes (e.g. stay and play).

Outcomes: 12 months: Primary=child BMI z-score; Secondary= parent and staff BMI and waist circumference, parenting self-efficacy, feeding, eating habits, quality of life, resource use, centre environment. Long-term (~3-years post registration): Child BMI z-score (NCMP/Health visiting data). Economic: cost per unit change in child BMI z-score, cost per unit change in weight after controlling for height, and the cost per change in obesity cases.

Qualitative systems process evaluations: including the development of systems map and evaluation of system response to HENRY with quantitative systems modelling to inform how HENRY can influence population obesity.

Analysis: ITT analysis will compare primary and secondary outcomes between arms using mixed effects linear regression as appropriate. Economic evaluation=1-year within-trial calculation of cost-per unit change in BMI z-score; long-term area under the curve and spillover impact; and longer-term trajectories to determine lifelong cost savings. Systems analysis=Qualitative thematic analysis and Morphological Analysis/Fuzzy Cognitive Mapping.

PPI: An established parent advisory group will support design, delivery, interpretation and dissemination of the research.

Timeline:73 months. Main study=60 months (primary reporting); 6 month dormant period; followed by 7 month long term follow-up.

Impact and dissemination: Dissemination and impact strategy will ensure clear pathways to impact, including; policy reports, dissemination events, community resources, social media and academic output.