Cluster randomised controlled trial, economic and process evaluation to determine the effectiveness and cost effectiveness of a novel intervention (Healthy Lifestyles Programme, HeLP) to prevent obesity in school children

DESIGN: Cluster randomised controlled trial with economic and process evaluation. Schools will be stratified by % of children eligible for free school meals and number of Year 5 classes and randomised within strata to intervention and control groups, by an independent statistician from the Clinical Trials Unit. The unit of randomisation will be schools rather than individual children and multi-level modelling will be applied during analysis to account for this. SETTING: State Junior/Primary schools in Devon and Plymouth; sample weighted towards schools from wards with highest indices of deprivation. TARGET POPULATION: Children aged 9-10 years, their parents and schools. INTERVENTION BEING EVALUATED: HeLP is a multi-component 4 phase Programme that seeks to create a receptive environment, targeting all children and their families, to enable the development and support of healthy lifestyle behaviours. The overarching concept emphasises achievable, sustainable behaviour change, concentrating on moving towards a healthy energy balance. Three key behaviours are emphasized and these are framed within the concept we label ‘80/20’, suggesting we should aim to maintain healthy behaviours 80% of the time. Phase 1 focuses on 'Creating a Supportive Context' for the school, child and family and involves a variety of delivery methods (assembly, activity workshops, parent’s evenings, and newsletter articles) to establish information, raise awareness, bolster motivation and build relationships. This takes place in the autumn term of Year 5. Phase 2, which takes place in the spring term, is the intensive 'Healthy Lifestyles Week' using education sessions in the morning delivered by the class teacher which link into drama workshops in the afternoon, delivered by a local theatre company, to increase motivation, knowledge and self efficacy and develop a number of skills to enable behaviour change. Phase 3 is 'Personal Goal Setting and Parental Support' and aims to develop planning skills, increase self awareness and increase parental support. Phase 4 is Reinforcement Activities” (assemblies, drama and education session, 1-to-1 goal review meetings and newsletter articles) which aims to develop monitoring and coping skills as well as consolidating parental support (see Table 1, section 3 detailed description). MEASUREMENT OF COST AND OUTCOMES: Height will be measured using a SECA stadiometer; weight and body fat will be measured using the Tanita Body Composition Analyser SC-330. Physical activity will be measured using accelerometry and food intake using the Food Intake Questionnaire (44). Mediating variables will be measured at 12 months, using a questionnaire assessing knowledge, attitudes, perceived norms behavioural intentions and diet and physical activity (see section 7 in the detailed description). The 18 and 24 month anthropometric measurements will be made by an independent assessor, blind to allocation. Resource use and costs associated with delivery of the intervention will be identified and measured within the trial. PROCESS EVALUATION: A process evaluation will be conducted to provide insight into the way HeLP works in terms of uptake, delivery and experience. This will include collection of quantitative and qualitative data to assess participation, engagement and experience of children, parents and teachers. PLANNED ANALYSES: The primary effectiveness analysis will be based on intention-to-treat and take account of clustering by schools and adjusting for relevant child and school level covariates and baseline scores. Results will be presented as between-group differences, at 18 and 24 months, with appropriate 95% confidence intervals. Framework analysis will be used to analyse the qualitative data. Cost-effectiveness analysis (CEA) will involve a within-trial economic analysis and the development of an economic model, with evidence synthesis, to assess the longer-term cost-effectiveness of HeLP. Within-trial analyses wil