OBJECTIVES: This study aims to identify practical, trauma-informed strategies to improve engagement of populations experiencing homelessness in observational health research.

DESIGN: Data from three real-world observational studies involving people experiencing homelessness (PEH) and housed participants were analysed for study completion rates and participant demographics. A team of researchers, clinicians and people with lived experience of homelessness, reviewed their experience of study design, recruitment and assessment study procedures to identify strategies found to be effective in recruitment and retention of PEH.

SETTING: The Inclusion Health Research Group (IHRG) consists of 10 clinicians and researchers who study the effect of social exclusion, such as homelessness, on health. Many members of the group also provide clinical care to PEH. The three observational studies which informed this paper recruited participants in Dublin, Ireland between 2021 and 2025. Approximately 15 000 adults are currently experiencing homelessness in Ireland, of whom two-thirds reside in Dublin and more than 70% are accommodated in hostels.

PARTICIPANTS: The three observational studies that informed this paper, designed and carried out by members of the IHRG, included populations of PEH recruited from sites in the community across Dublin.

RESULTS: PEH were predominantly male with an average age in their mid-40s and a high prevalence of smoking, drug use and alcohol consumption. Study completion rates were high (83.3% to 94.1%). On review of the study design and implementation, eight key strategies were identified as effective in recruitment and retention of PEH: (1) involvement of people with lived experience in study design; (2) flexible recruitment locations; (3) flexible assessment timings; (4) trust-building through consistent communication; (5) collaboration with gatekeeper organisations and peer advocates; (6) use of non-financial incentives like health screenings; (7) validated assessment tools and (8) tailored support for participants with addiction.

CONCLUSIONS: Using flexible, trauma-informed, participant-centred approaches informed by the involvement of people with lived experience and gatekeeper organisations can ensure high levels of recruitment and retention of PEH. This may enhance research inclusivity and ultimately contribute to better understanding of the complex health needs of populations experiencing homelessness within public health.