Protocol for a feasibility cluster randomised controlled trial of a peer-led school-based intervention to increase the physical activity of adolescent girls (PLAN-A)

Background: Physical activity levels are low amongst adolescent girls and this population face specific barriers to being active. Peer influences on health behaviours are important in adolescence and peer-led interventions might hold promise to change behaviour. This paper describes the protocol for a feasibility cluster randomised controlled trial of PLAN-A, a peer-led intervention aimed at increasing adolescent girls’ physical activity levels.

Methods/Design: A two-arm cluster randomised feasibility trial will be conducted in six secondary schools (intervention n = 4; control n = 2) with Year 8 (12-13 year-old) girls. The intervention will operate at a year group level and consist of Year 8 girls nominating influential peers within their year group to become peer-supporters. Approximately 15% of the cohort will receive three days of training about physical activity and interpersonal communication skills. Peer-supporters will then informally diffuse messages about physical activity amongst their friends for ten weeks. Data will be collected at baseline (T0), immediately after the intervention (T1) and 12 months after baseline measures (T2). In this feasibility trial the primary interest is in the recruitment of schools and participants (both Year 8 girls and peer-supporters), delivery and receipt of the intervention, data provision rates and identifying the cost categories for future economic analysis. Physical activity will be assessed using seven day accelerometry, with the likely primary outcome in a fully-powered trial being daily minutes of moderate-to-vigorous physical activity. Participants will also complete psychosocial questionnaires at each time point; assessing motivation, self-esteem and peer physical activity norms. Data analysis will be largely descriptive and focus on recruitment, attendance and data provision rates. The findings will inform the sample size required for a definitive trial. A detailed process evaluation using qualitative and quantitative methods will be conducted with a variety of stakeholders (i.e., pupils, parents, teachers and peer-supporter trainers) to identify areas of success and necessary improvements prior to proceeding to a definitive trial.

Discussion: This paper describes the protocol for the PLAN-A feasibility cluster-randomised controlled trial which will provide the information necessary to design a fully-powered trial should PLAN-A demonstrate evidence of promise.

Trial Registration: ISRCTN12543546