Overdose prevention centres as spaces of safety, trust and inclusion: A causal pathway based on a realist review.

Issues: Overdose prevention centres (OPC) are non-residential spaces where people can use illicit drugs (that they have obtained elsewhere) in the presence of staff who can intervene to prevent and manage any overdoses that occur. Many reviews of OPCs exist but they do not explain how OPCs work.

Approach: We carried out a realist review, using the RAMESES reporting standards. We systematically searched for and then thematically analysed 391 documents that provide information on the contexts, mechanisms and outcomes of OPCs.

Key Findings: Our retroductive analysis identified a causal pathway that highlights the feeling of safety - and the immediate outcome of not dying - as conditions of possibility for the people who use OPCs to build trust and experience social inclusion. The combination of safety, trust and social inclusion that is triggered by OPCs can - depending on the contexts in which they operate - generate other positive outcomes, which may include less risky drug use practices, reductions in blood borne viruses and injection-related infections and wounds, and access to housing. These outcomes are contingent on relevant contexts, including political and legal environments, which differ for women and people from racialised minorities.

Conclusions: OPCs can enable people who live with structural violence and vulnerability to develop feelings of safety and trust that help them stay alive and to build longer term trajectories of social inclusion, with potential to improve other aspects of their health and living conditions.