Community-engaged participatory methods for embedding equity in trial design

BACKGROUND: Certain populations are consistently under-represented in randomised controlled trials (RCTs), including people from minority ethnic backgrounds and those experiencing socioeconomic disadvantage, language barriers, or marginalisation within health systems. This under-representation contributes to widening health inequities. While UK guidance such as the National Institute for Health and Care Research INCLUDE resources supports more inclusive research, practical methodologies for embedding equity in trial design remain limited. This paper draws on two linked public involvement projects: Talking Trials (2021-2023), working with ethnically diverse urban communities in Cardiff, and Let's Talk Research (2025), working with residents in a socioeconomically disadvantaged rural Welsh community. METHODS: Both projects used participatory methods including arts-based activities, deliberative dialogue, and co-production. Talking Trials incorporated thematic analysis of workshop reflections; both projects generated learning through reflective discussions with community partners. RESULTS: Community-based public contributors identified features that made research feel relevant and equitable: trusted relationships, time for dialogue, and support to understand complex concepts. Creative and dialogue-based approaches made research concepts accessible, reduced power imbalances, and supported contributors to move from unfamiliarity to active involvement. Sustained structures, such as advisory groups and community connectors, were important for maintaining trust and enabling continued engagement. Context strongly shaped involvement, with different forms of disadvantage requiring different types of support. CONCLUSIONS: Community-engaged, arts-based, and context-sensitive methods can meaningfully enhance equity in trial design. Embedding involvement early, investing in trusted partnerships, and sustaining long-term structures support more relevant, acceptable, and inclusive trials. These findings offer practical methodologies for trial teams seeking to embed equity from the outset.