Housing is an important determinant of health that has been linked to a variety of poor health outcomes. Research indicates that living situations such as homelessness and marginal housing (e.g., single-room occupancy housing) are associated with a higher prevalence of chronic and infectious diseases and poorer overall mental and physical health. Estimates of substance use among individuals experiencing homelessness vary depending on the population and definition of homelessness used, but there is consistent evidence that individuals experiencing homelessness report disproportionate rates of substance use. A 2008 meta-analysis of international studies found that 4.5–54.2% of individuals experiencing homelessness reported non-alcohol substance use, substantially higher than the estimated overall prevalence of substance use.440 Within BC, 8,665 people were enumerated as homeless in 2020/21 and over two-thirds (67%) of respondents indicated they had some form of addiction, although both of these numbers are considered to be underestimates.441

Current evidence suggests substance use and homelessness are mutually-reinforcing, but evidence is mixed regarding causality, including the temporality and magnitude of the relationship between substance use and homelessness.442 However, housing instability that precedes substance use is linked to increased drug use intensity, including initiation into injection drug use. Compared to the general population, individuals who experience homelessness have higher substance-related mortality rates, including opioid overdose as a leading cause of death.443,444 

Individuals experiencing homelessness face significant barriers accessing and being retained in OUD care, despite utilizing health care services—particularly emergency services—more frequently than housed individuals.445 Further, people experiencing homelessness face challenges in accessing health care services, including lack of knowledge regarding care options, lack of transportation, lack of child care, and previous and anticipated experiences of discrimination in health care settings.445 Specific aspects of OUD care (e.g., frequent appointments with clinicians, daily visits to a pharmacy to pick up OAT medication) present further barriers to treatment access for individuals who experience homelessness. Clinicians can better support individuals who experience homelessness by working collaboratively with patients to determine a treatment plan, providing flexible appointments, and prescribing take-home doses of medications, if appropriate (see Appendix 6 for details on take-home dosing).  People who experience homelessness who present in emergency departments may be candidates for an emergency department buprenorphine/naloxone induction (see Emergency Department Buprenorphine/Naloxone Induction and Appendix 4). Clinicians should connect patients with resources to meet their other health, social, and survival needs (e.g., specialist care, housing, food/nutrition, financial assistance, employment, outreach services) as requested or appropriate.