What does it take to successfully retain organisational cluster sites? A mixed-methods, collective case study examining retention processes in the Reducing Smoking Initiation in Young Adults RCT

Achieving high retention rates in cluster trials is challenging. Evidence in the literature predominantly addresses participant-level retention and theoretical insight into the dynamics of effective retention is missing. This thesis aimed to investigate how successful cluster retention happens, and offer theoretical explanations for retention.
A systematic review was conducted which identified strategies to promote cluster-level retention. Whilst some participant-level strategies were generalisable to clusters, five uniquely cluster-related, additional strategies were found. Cluster retention was found to be under-researched, particularly researchers’ experiences of managing clusters. Participants’ voices and relational aspects of retention also appeared to be under-represented.
A collective case study design was used to scrutinise processes operating within a school-based, pragmatic cluster RCT with successful retention outcomes. Key stakeholders’ trial experiences were investigated through interviews, focus groups and documentation analysis. Study 1 identified that personal qualities of in-site teacher-coordinators and the researchers’ extensive investment in these relationships appeared to support retention, even in ‘unhealthy’ organisational contexts. In study 2 trial staff reported perceiving an ever-present risk of disengagement, with retention demanding complex, hidden intrapersonal and relational work. Interviews with teachers delivering the intervention/control in Study 3 highlighted their significant personal responsibility for student engagement. Student focus group findings (Study 4) suggested that school engagement builds classroom-by-classroom: student engagement was contingent on teachers’ ability/willingness to create a supportive climate and ‘make the lesson work’. Study 5 reported a positive impact on school engagement of a £39,000 Engagement Promotion Programme. Schools valued highly complex skills exchanges and services, beyond transactional objects.
Evidence from the thesis suggests that multiple inter-relational complexities influence site retention, beyond traditional transactional strategies. Cluster trials are re-interpreted as inter-organisational collaborations and the task of retention more accurately defined as risk management. Retention is theorised as resulting from extensive relational work, meaningful social exchange and social influence.