Implementation of the Trigger Checklist and assertive outreach to reduce drug-related harm in the Emergency Department: A realist evaluation

Background: Drug-related harm is a major global public health concern, with opioids implicated in over 70% of drug-related deaths. Scotland reports the highest drug-related mortality rate in Europe, with remote and rural communities facing additional barriers to accessing harm reduction and treatment services. Assertive outreach is increasingly recognised as a key strategy to engage individuals at risk who are disconnected from traditional services. This study evaluates the use of a Trigger Checklist to identify and outreach individuals within 48 hours of referral in a rural Emergency Department (ED). Methods: A realist evaluation explored how and why the Trigger Checklist works within the complexity of an ED setting. Guided by Pawson and Tilley’s framework, the evaluation followed three stages: theory gleaning, refining, and consolidation. Initial programme theories were developed using literature and advisory group input, then refined through 13 realist interviews with ED clinicians and outreach workers (OW). Data were analysed using Context-Mechanism-Outcome (CMO) configurations and linked to middle-range theories. Results: Three programme theories emerged: (1) Confident decision-making, where certainty, conversational aids, ethical reasoning, and outreach worker prompts influenced checklist use; (2) Trusting relationships, shaped by OWs’ approachability, situational awareness, and mutual respect; and (3) Perceived value, driven by altruism, narrative feedback, and perceived reductions in ED visits. Relational coordination theory explained how shared goals, knowledge, and respect – reinforced by timely, accurate communication – enabled coordinated action. OW presence and recovery discussions were critical to foster confident and appropriate referrals among ED clinicians. Conclusions: The Trigger Checklist can support timely outreach potentially reducing drug-related harm in rural ED settings, but its success depends on relational dynamics, perceived value, and organisational integration. To avoid checklist fatigue or tokenistic use, it should be embedded with the support of OWs who foster trust. These relationships will enhance use of the checklist as a meaningful intervention within complex care systems.