Defining terminology and outcome measures for evaluating overdose response technology: An international Delphi study

Introduction: Various novel harm reduction services leverage technology to reduce the rising number of drug poisoning deaths, particularly among those who use drugs alone. There is significant variability in terminology and outcome measures in reporting these interventions, complicating efforts to build a comprehensive knowledge base. Thus, we conducted a Delphi study to establish consensus and heterogeneity in these metrics. Methods: Panellists from three stakeholder groups (people who use drugs, virtual harm reduction service operators and academics) participated in a multi-round Delphi study. The first round included open-ended questions to propose items in three categories: terminology, demographic information and outcomes. Subsequent rounds included options from a previously conducted scoping review for consideration. Likert ratings were used to achieve consensus, with a 70% threshold. Final rounds involved ranking terminology that reached a consensus. Results: Of 23 initial participants, 14 completed the fourth survey round. “Overdose response technology” was identified as the most appropriate term for these harm reduction technologies. This definition includes drug contamination alerts, overdose response hotlines and applications, wearable overdose detection technology and overdose detection tools. Fourteen demographic outcomes reached a consensus for data collection, including name or handle, neighbourhood, age, gender, past overdose experience, substance used, amount and route of use. Six service use outcomes were recommended: response type, service outcomes, morbidity and mortality, overdose events, responder arrival time and post-rescue care. Discussion and Conclusions: The study results are recommended to standardise terminology and guide future research and knowledge dissemination in the field, ensuring clear communication with a shared language.