Recruiting to a large-scale physical activity randomised controlled trial – experiences with the gift of hindsight

Background: Recruitment issues continue to impact a large number of trials. Sharing recruitment information is vital to support researchers to accurately predict recruitment and to manage the risk of poor recruitment during study design and implementation. The purpose of this paper is to build on the knowledge available to researchers on recruiting to community based trials. Methods: A critical commentary of the recruitment challenges encountered during the ‘Booster’ Study, a randomised controlled trial which investigated the effectiveness of a Motivational Interviewing style intervention on the maintenance of physical activity. An overview of recruitment is provided, as well as strategies employed to recruit prospective participants and possible barriers to recruitment. Results: Two hundred and eighty two people, 47% of the original target, were recruited through mail-outs with secondary recruitment pathways yielding no additional participants. The research team encountered problems re-contacting interested participants and providing study materials in non-English languages. A lower response rate to the mail-out and a greater number of non-contactable participants in the full study compared to the pilot study resulted in a smaller pool of eligible participants from the brief intervention eligible for recruitment into the RCT. Conclusion: Despite utilising widely accepted recruitment strategies and incorporating new recruitment tactics in response to challenges, the ‘Booster’ study failed to randomise a sufficient number of participants. Recruitment to community based, behavioural interventions may face different challenges than trials based in clinical or primary care pathways. Specific challenges posed by the complexity of the study design and problems with staffing and resources were exacerbated by the need to revise upwards the number of mailed invitations as a result of the pilot study. Researchers should ensure study design is facilitative to recruitment and consider the implications of changing recruitment on the operational aspects of the trial. Where possible the impact of new strategies should be measured, and recruitment successes and challenges shared with those planning similar studies. The study was a registered controlled trial (ISRCTN56495859 12 Feb 2009; NCT00836459 03 Feb 2009) KEYWORDS: Recruitment, Physical Activity, mail-outs, BOOSTER, behaviour maintenance,