'People ring because they're frightened': findings from a realist evaluation on the impact of timely responsive care at home at the end of life.

Background: Rapid response services (RRS) support patients who wish to die at home, providing flexible, timely, and specialist care. These services are regionally variable yet are valued by patients and caregivers in often uncertain end-of-life situations. Research on their effectiveness and implementation to date is limited. This study explores how RRS are experienced in practice and identifies key contexts and mechanisms underpinning their impact.

Objectives: This study aimed to understand how different service models of RRS function, who they work for, how and why. By exploring patient, caregiver, and staff perspectives, we sought to refine programme theories and provide evidence-based recommendations for service improvement and policy development.

Design: A realist evaluation approach was used to examine how, why, and in what contexts RRS provide end-of-life care. Through iterative theory development and refinement, we identified key generative mechanisms and the contexts in which they trigger outcomes.

Methods: Qualitative data were collected via realist theory driven semi-structured focus groups and interviews with 36 participants across two sites, each operating a distinct RRS model. Data were analysed using a retroductive context-mechanism-outcome (CMO) framework and informed by Transitions Theory.

Results: Six programme theories were developed, highlighting the central role of continuity of care in enabling positive end-of-life experiences. A sense of 'being known' by RRS staff facilitated smooth transitions, reduced distress, and fostered trust. Timely, responsive care, particularly at night, was valued, whereas gatekeeping, fragmented service models, and inequities in access (especially for non-cancer patients) created barriers.

Conclusions: Patients and caregivers valued holistic, relationship-centred care that provided emotional security alongside practical support. However, service inconsistencies, late transitions into palliative care, and systemic inequities limit accessibility. Findings highlight the need for early engagement, integrated service models, and 24/7 specialist care, ensuring greater continuity and equity in home-based end-of-life care.