title: Update to a 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).
abstract: BACKGROUND
  Physical activity levels are low amongst adolescent girls, and this population faces 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 Peer-Led physical Activity iNtervention for Adolescent girls (PLAN-A), a peer-led intervention aimed at increasing adolescent girls' physical activity levels. In addition, this paper describes an update that has been made to the protocol for the PLAN-A feasibility cluster randomised controlled trial.
  
  
  METHODS
  A two-arm cluster randomised feasibility trial will be conducted in six secondary schools (interventionn= 4; controln= 2) with year 8 (12-13 years 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 3 days of training about physical activity and interpersonal communication skills. Peer supporters will then informally diffuse messages about physical activity amongst their friends for 10 weeks. Data will be collected at baseline (time 0 (T0)), immediately after the intervention (time 1 (T1)) and 12 months after baseline measures (time 2 (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 7-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.
  
  
  CONCLUSIONS
  The study will provide the information necessary to design a fully powered trial should PLAN-A demonstrate evidence of promise. This paper describes an update to the protocol for the PLAN-A feasibility cluster randomised controlled trial related to the data-linkage component.
  
  
  BACKGROUND
  ISRCTN12543546.
authors.affiliation: Centre for Exercise, Nutrition & Health Sciences, School for Policy Studies, University of Bristol, Bristol, UK.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Sebire
authors.affiliation: Centre for Exercise, Nutrition & Health Sciences, School for Policy Studies, University of Bristol, Bristol, UK.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Edwards
authors.affiliation: School of Social & Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Rona
authors.initials: R
authors.lastname: Campbell
authors.affiliation: Centre for Exercise, Nutrition & Health Sciences, School for Policy Studies, University of Bristol, Bristol, UK.
authors.forename: Russell
authors.initials: R
authors.lastname: Jago
authors.affiliation: School of Social & Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Ruth
authors.initials: R
authors.lastname: Kipping
authors.affiliation: Centre for Exercise, Nutrition & Health Sciences, School for Policy Studies, University of Bristol, Bristol, UK.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Banfield
authors.affiliation: School of Social & Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Bryar
authors.initials: B
authors.lastname: Kadir
authors.affiliation: School of Social & Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Kirsty
authors.initials: K
authors.lastname: Garfield
authors.affiliation: Farr Institute, Swansea University Medical School, Swansea, UK.
authors.forename: Ronan A
authors.initials: RA
authors.lastname: Lyons
authors.affiliation: School of Social & Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Blair
authors.affiliation: School of Social & Community Medicine, University of Bristol, Bristol, UK.
authors.forename: William
authors.initials: W
authors.lastname: Hollingworth
keywords: Adolescent girls; Intervention; Peers; Physical activity; School