Keeping it credible in cohort multiple Randomised Controlled Trials: the Community Ageing Research 75+ (CARE 75+) study model of patient and public involvement and engagement.

Background There is increasing guidance on how to make the most of the rich seam of data provided by large cohort studies, and growing recognition of the benefits of cohort multiple Randomised Controlled Trials (cmRCT) in health research. In contrast, there is a lack of discussion about patient and public involvement and engagement (PPIE) in these large and complex research infrastructures. Our aim was to create a structure to enable meaningful, sustainable public involvement within the cmRCT framework. We have established a core reference group of four key individuals with extensive links to other relevant local community structures and individuals. Results Using the CARE 75+ model we have engaged with a wide variety of patients and the public in a relatively short space of time. Activities have included scrutiny of protocols and assessment tools, and process evaluations; resulting in system efficiencies, increased recruitment and a more focused research agenda. Conclusions There is a need for strong public oversight and flexible models of PPIE in cmRCTs. The model of PPIE developed in the Community Ageing Research 75+ study presents one potential way to foster expertise and enable diversity.