Title: 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
Funder: Department of Health (England)

Abstract: 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 will provide a robust estimate of the costs associated with delivery of the HeLP intervention presenting a mean incremental cost per school / per child. CEA will relate incremental costs to incremental health outcomes (e.g. cost per unit of BMI change cost per change in proportion of overweight/obese). Modelling will link effectiveness outcomes to weight status over time (child to adult) and the impact of weight status on health outcomes (eg prevention of adult overweight/obesity diabetes CHD) with costs and QALYs for health outcomes over time informing the CEA in a policy-relevant way (eg cost per life-year cost per QALY). Modelling will build on existing studies in this area (45-47) although further development of the modelling framework will be undertaken using available observational and epidemiological data (48 49).SAMPLE SIZE: To have 90% power and 2-sided 5% significance level to detect a between-group difference in BMI SDS of 0.25 units at 24 months assuming a standard deviation of 1.3 an ICC of 0.02 allowing for an attrition rate of 20% and adjusting for baseline BMI SDS requires 952 children to be recruited (36). Also allowing for possible attrition of schools we will aim to recruit 32 schools to ensure we have 28 schools including 980 children and their families (based on an average of 35 children per school). A difference of 0.25 units in BMI SDS has been shown to be a meaningful change impacting on improvement in adiposity and metabolic health (37). The mean between-group difference in BMI SDS of ~-0.2 units (95% CI -0.5 to 0.1) at 24 months in our exploratory trial demonstrates such an effect size to be plausible (23). Whilst we had an 8% attrition rate in our exploratory trial we have allowed for a conservative attrition rate of 20% in our sample size calculation.PROJECT TIMETABLES:Months 1-5 Agree final protocol; secure ethical and research governance approval attend regional association of primary head teachers meetings agree standard operating procedures with the CTU.Months 3-10 Recruit and train trial staff recruit schools and children to trial randomise schools gain consent collect baseline measures; allocation revealedMonths 11-46 Deliver intervention collect 12 18 and 24 month outcome and process data Months 47-56: Check clean and analyse data; write report feedback results to participants consider policy and roll-out implications


Research activity codes: 3.1 PRIMARY PREVENTION INTERVENTIONS TO MODIFY BEHAVIOURS OR PROMOTE WELL-BEING
Health categories: STROKE;CANCER AND NEOPLASMS;METABOLIC AND ENDOCRINE;CARDIOVASCULAR;ORAL AND GASTROINTESTINAL