Abstract
INTRODUCTION: Stakeholder involvement in research processes is widely recommended to enhance the relevance, quality and uptake of research findings. However, existing studies highlight persistent challenges in engaging family caregivers in co-design research. This gap may result in research outcomes that fail to reflect family caregivers' needs and preferences, contradicting the core purpose of co-design. Therefore, the aim of this systematic review is to synthesise the available evidence on family caregivers' experiences of involvement in co-design research and to generate evidence-based strategies to support effective engagement. METHODS AND ANALYSIS: This systematic review will be conducted using a meta-aggregative approach, following the Joanna Briggs Institute's (JBI's) Manual for Evidence Synthesis. Systematic searches will be conducted in PubMed, CINAHL, Scopus, Web of Science and PsycINFO, with no date restrictions. Preliminary searches were performed in EMBASE between September and October 2025. Qualitative primary studies that explore family caregivers' experiences of involvement in co-design research will be included. Study selection and quality appraisal will be performed independently by two researchers using predefined protocols, disagreements will be resolved through discussion with a third reviewer. After calibration, a single reviewer will extract the data using a customised data extraction template with the dataset distributed among the authors. The first author will then review all extractions. Data will be analysed following JBI's meta-aggregative method, and results will be presented in narrative summaries, tables and diagrams. The findings will inform strategies for stakeholder involvement in future co-design research. Family caregivers and co-design researchers will be involved in reviewing and revising generated recommendations to enhance their relevance and practical utility. ETHICS AND DISSEMINATION: This protocol does not involve human participants. The findings of this review will be submitted for publication in a peer-reviewed journal and presented at relevant scientific conferences and meetings. PROSPERO REGISTRATION NUMBER: CRD420251229190.