This study will test whether parent engagement (recruitment, attendance) in a Childhood obesity prevention programme (HENRY) can be improved in local authorities randomised to receive an Optimisation intervention (in addition to standard HENRY) compared to those continuing to deliver the programme as standard.

BACKGROUND: Rising rates of obesity in preschool children are alarming and emphasise the need for evidence-based approaches to prevent obesity, which can be successfully implemented in communities. Although robust, theory-based prevention programmes exist, it is often a challenge to get parents to attend them and adopt positive behaviour changes in their families.

AIM: To evaluate the effectiveness of a recently developed 'Optimisation intervention' to optimise parent engagement in a community based obesity prevention programme 'HENRY', using routinely collected process data from existing sites commissioned to deliver HENRY in the UK

DESIGN: Multi-centre, cluster randomised controlled trial. As research will judge the ability of local authorities and their Centres to optimise implementation of HENRY, a cluster randomised design, has been chosen with local authority as the unit of randomisation. Local authorities will be randomised in a 1:1 allocation ratio (HENRY+ Optimisation Intervention; HENRY alone control) by a statistician at Leeds CTRU, using minimisation algorithm with random element, stratifying on baseline level of implementation (proportion of Centres meeting none of the 2 primary outcome implementation criteria/ meeting 1 or 2 of the criteria)) size of local authorities (number of Children's Centres (< 10/ ≥10)) and area deprivation (≤10% />10% ranking within Index of Multiple Deprivation at the Lower Layer Super Output Area).

Consent to participate will be sought at the cluster level (local authorities) and from the Centres within each local authority using an opt-out approach.

CONTROL ARM: HENRY delivered as standard. HENRY (Health, Exercise, Nutrition for the Really Young) is an 8-week programme delivered in Children's Centres (CCs), aiming to provide parents with skills and knowledge to support healthy lifestyles in preschool children and their families. It was set up in 2006 with Department of Health support aimed at reversing rising trends in school entry age obesity. HENRY is currently delivered in 32 local areas across England and Wales by trained health and community practitioners.

ACTIVE ARM: HENRY as standard plus an optimisation intervention to enhance parent engagement (recruitment and attendance) in the 8 week programme. A tailored 'Optimisation' intervention has been developed with a NIHR funds (CDF 2014-07-052) to support local authorities and Children's Centres to promote HENRY implementation, based on observations of positive deviants, interviews with Children Centre staff and other stakeholders, and input from parents. The resulting optimisation package is a multi-component intervention implemented at multi-levels (local authorities, Centres, parents). Precise details can not currently be disclosed to do risk of contamination.

ANALYSIS: Primary outcome analysis will be on the intention-to treat Population using a 3-level hierarchical model, with courses (or participants) nested within CCs within LA, adjusting for randomization minimisation variables. Differences in parent engagement, corresponding 95% CI, p-values and ICCs will be reported.

Inclusion Criteria:

Local authorities:

• Local authorities providing data from at least 4 Children's Centres
• Courses delivered by trained staff who have been certified by HENRY

Children's Centres:

• At least one course to be delivered per Centre per year
• Sites with a history of providing process data for the previous year.

There will be no exclusions based on the demographics of Children's Centres, but location will be monitored to ensure inclusion of those with diverse social and environmental characteristics.

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Exclusion Criteria:

Local authorities:

• Areas which have plans to decommission the HENRY intervention during the course of the trial; or who are not planning on running HENRY programmes during the trial period.

Children's Centres:

• Centres where ethnography has taken place during Study 2
• Centres who are not planning on running HENRY programmes during the trial period

Data IP is held with the HENRY organisation