Fostering equitable access to palliative care for people experiencing homelessness and serious illness: a multi-method, citizen science study using a theory of change approach

Background In Germany, there are currently over 531,000 people experiencing homelessness (PEH), with a high burden of physical illness, mental illness and substance use, often occurring simultaneously as trimorbidity. PEH face substantial barriers to healthcare and frequently access palliative care (PC) late or not at all. These challenges require approaches that account for complex health and social needs and fragmented care structures. However, co-produced, practice-ready, and transferable approaches remain rare. This study aims to identify current issues and needs in PC provision for PEH in Münster, Germany and to develop a Theory of Change (ToC) to inform future improvements in care. Methods This is an investigator-initiated, multi-method study conducted in Germany. Citizen Scientists and frontline staff co-designed the study, co-facilitated the empirical research and joined analysis and workshops. We hosted a cross-sector World Café ( n = 18) and conducted in-depth interviews ( n = 5) with people living with serious illness and homelessness. World Café material was analysed using reflexive thematic analysis. Interviews were analysed using a constructivist Grounded theory informed approach. A ToC was developed iteratively throughout the whole project in recurrent meetings. Results The World Café mapped three dominant problem fields and two enabling conditions. Problem fields: (i) structural constraints (bureaucracy, financing, weak inter-agency links, medication governance); (ii) access and trust (unclear contact points, communication barriers, low appointment reliability); (iii) bio-psycho-social complexity (addiction, multimorbidity, autonomy vs. help-seeking, stigma). Enablers: (iv) emotionally supported staff and (v) coordinated networking with low-threshold outreach. The Grounded theory informed analysis resulted in a theoretical model of “living with serious illness and homelessness” spanning: needs (safety/quiet/privacy, trusted persons, material support), current support (social-work brokerage, accommodation access, outpatient care, health insurance), worries (progression, loneliness, loss of meaning), issues in care (unstable housing, hygiene, administrative waits) and wishes (safe, accepting, eye-level encounters). The co-produced ToC specifies inputs (stakeholder engagement, outreach), mechanisms (relationship-centred practice, stigma awareness, cross-sector coordination) and proximal outcomes (continuity, earlier identification, staff competence). Conclusions Citizen Science partners delineated a pragmatic, mechanism-focused research and ToC with modular components that support scaling and adaptation across regions.