In recent years, the homelessness crisis has escalated, with increased numbers of people entering homelessness and need for comprehensive interventions that meet the complex health challenges faced by people experiencing homelessness in Ireland. This document, guided by national strategic objectives and international best practice, sets out a number of principles, priorities, and actions aimed at supporting a collaborative response to the homelessness crisis, including the delivery of planned, long-term action and integrated quality healthcare initiatives that meet the needs of the changing profile of people experiencing homelessness. In line with the principles that underpin the work of the HSE National Social Inclusion Office (NSIO), this document outlines the importance of social determinants on the overall health and wellbeing of individuals. Every individual has a right to housing, and it is well established that suitable housing conditions are a key determinant of health. In line with the Housing for All: A New Housing Plan for Ireland (2021), the HSE will continue to work with colleagues in Local Authorities, the Department of Housing, and the Department of Health to deliver the Housing First programme, which provides housing to individuals experiencing homelessness along with intensive wrap-around and comprehensive provision of services to support individuals in their own homes and prevent homelessness and ill health. Collaborative working relationships with partners that equally seek to address social determinants of health are key to the prevention and management of the health burden in socially excluded groups.

P.10 3.2.1 Mental Health, Dual Diagnosis, and Addiction - Persons experiencing homelessness have a higher number of mental health issues than the general population (CSO, 2016). Data from the HSE’s National Office for Suicide Prevention (NOSP) shows that 2% of people who died by probable suicide from 2015 to 2018 were identified as being homeless at the time of death – this includes sleeping rough and staying in hostels or supported accommodation (Cox, Munnelly, Rochford and Kavalidou, 2022). The National SelfHarm Registry has observed a yearly increase in the proportion of presentations to hospitals as a result of self-harm by persons experiencing homelessness, at 7.5% of all hospital self-harm presentations in 2020 (Joyce et al., 2022). Especially vulnerable are people with dual diagnosis (co- morbid disorders due to substance use and/ or addictive behaviours, along with the presence of a mental disorder). The National Institute for Health and Care Excellence (NICE) guidelines outline a set of recommendations on integrated health and social care for people experiencing homelessness. According to the 2022 guidelines, the eligibility criteria should not exclude from services people experiencing homelessness who have co-morbid mental health and substance misuse issues. While not all individuals experiencing homelessness use substances, O’Reilly et al. (2015) estimated that 80% of people experiencing homelessness in Dublin had a history of past or current drug use. In addition, there is an intersection between homelessness and high-risk drug use among people experiencing chronic and episodic (recurrent) homelessness (European Monitoring Centre for Drugs and Drug Addiction [EMCDDA], 2022).

The foundational principles for effective addiction services for individuals experiencing homelessness typically revolve around ensuring stable housing, implementing harm reduction measures, and employing integrated approaches. Stable housing is recognized as a crucial element for both treatment success and social integration, as releasing individuals from treatment into homelessness or providing treatment without housing can exacerbate existing challenges. Delivering harm reduction services to this demographic is most effective when offered through easily accessible, low-threshold services that are responsive to clients’ needs. Integrated strategies go beyond singular interventions by establishing interconnected support networks that link various services, such as housing, addiction treatment, and psychosocial support, tailored to each client’s specific requirements (EMCDDA, 2022). Additionally, recent evidence review exploring international evidence for responding to substance use among people who are homeless, concluded that service integration and flexibility in service delivery are key to meeting this group’s needs (Miler et al., 2021). As drug markets evolve, it becomes increasingly vital to monitor substance use trends and develop appropriate responses, particularly among homeless populations. The landscape of drug use is shifting, marked by the emergence of New Psychoactive Substances and a rising number of individuals seeking support for crack cocaine use...