Effectiveness and cost-effectiveness of the PLAN-A intervention, a peer led physical activity program for adolescent girls: Results of a cluster randomised controlled trial

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Background: Physical activity is associated with improved health. Girls are less active than boys. Pilot work showed that a peer-led physical activity intervention called PLAN-A was a promising method of increasing physical activity in secondary school age girls. This study examined the effectiveness and cost-effectiveness of the PLAN-A intervention.

Methods: We conducted a cluster randomised controlled trial with Year 9 (13-14 year old), girls recruited from 20 secondary schools. Schools were randomly assigned to the PLAN-A intervention or a non-intervention control group after baseline data collection. Girls nominated students to be peer leaders. The top 18% of girls nominated by their peers in intervention schools received three days of training designed to prepare them to support physical activity. Data were collected at two time points, (T0) and 5-6 months post-intervention (T1). Participants wore an accelerometer for seven days to assess the primary outcome of mean weekday minutes of moderate-to-vigorous physical activity (MVPA). Multivariable mixed effects linear regression was used to estimate differences in the primary outcome between the two arms on an Intention-to-Treat (ITT) basis. Resource use and quality of life were measured and a within trial economic evaluation from a public sector perspective was conducted.

Results: A total of 1558 girls were recruited to the study. At T0, girls in both arms engaged in an average of 51 minutes of MVPA per weekday. The adjusted mean difference in weekday MVPA at T1 was -2.84 minutes per day (95% CI = -5.94 to 0.25) indicating a slightly larger decline in weekday MVPA in the intervention group. Results were broadly consistent when repeated using a multiple imputation approach and for pre-specified secondary outcomes and sub-groups. The mean cost of the PLAN-A intervention was £2817 per school, equivalent to £31 per girl. Economic analyses indicated that PLAN-A did not lead to demonstrable cost-effectiveness in terms of cost per unit change in QALY.

Conclusions: This study has shown that the PLAN-A intervention did not result in higher levels of weekday MVPA or associated secondary outcomes among Year 9 girls. The PLAN-A intervention should not be disseminated as a public health strategy.
Original languageEnglish
Article number63
Number of pages13
JournalInternational Journal of Behavioral Nutrition and Physical Activity
Issue number1
Publication statusPublished - 13 May 2021

Bibliographical note

Funding Information:
This project was funded by the National Institute for Health Research (Public Health Research Programme) (project number 17/50/01). RJ and WH are partly funded by National Institute for Health Research Applied Research Collaboration West (NIHR ARC West) at University Hospitals Bristol NHS Foundation Trust and the University of Bristol. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the Public Health Research Programme, NIHR, NHS or the Department of Health and Social Care. Intervention costs have been funded by Sport England. This study was designed and delivered in collaboration with the Bristol Randomised Trials Collaboration (BRTC), a UKCRC Registered Clinical Trials Unit which, as part of the Bristol Trials Centre, is in receipt of National Institute for Health Research CTU support funding. The costs of delivering the intervention were funded by Sport England.

Publisher Copyright:
© 2021, The Author(s).

Structured keywords

  • SPS Exercise, Nutrition and Health Sciences


  • physical activity
  • peers
  • adolescent girls
  • intervention
  • school


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