Definition of mass-casualty incidents and classification of criteria

OBJECTIVE: The aim of this study is to revise the current criteria used by the Health Coordination Center in Disaster (HCCD) for defining mass casualty incidents (MCIs) in Türkiye, and to provide an updated approach for MCI characterization. MATERIALS AND METHODS: This study employed the Delphi method, a consensus-building technique, involving 21 emergency physicians (EPs), and 2 AI systems. RESULTS: Through expert consensus, the HDCC criteria were divided into primary and secondary event criteria, and new criteria were added. Primary mass casualty incident criteria: sudden events, incidents involving 10 or more deaths, 100 or more injuries, situations requiring responses beyond local capacity, terrorist attacks, environmental disasters, Chemical, Biological, Radiological, and Nuclear-Explosion (CBRN-E) incidents, fires, mass Carbon Monoxide poisoning incidents, and events requiring international assistance. Secondary mass casualty incident criteria: climate change-related disasters, land, sea, rail, or air transport accidents, public protests or events, explosions, search and rescue operations, mass food, water, or air poisoning incidents, mining accidents, technological accidents and cyber threats, incidents involving emergency medical services (EMS) personnel, events causing regional or national socio-economic loss, damage to critical infrastructure (hospitals, bridges, power plants, etc.), long-term health, psychological, or social issues, and incidents affecting vulnerable groups (such as the elderly, children, or disabled individuals). For primary events, it was generally recommended that activation decisions be made directly on-site, while for secondary events, activation decisions should be made by centralized authorities such as the Provincial HDCCs. CONCLUSION: This study re-evaluated and updated the HDCC criteria used in Türkiye for the definition of mass casualty incidents based on expert consensus. The categorization of MCI criteria into primary and secondary events enables the development of more rapid and effective response strategies based on the urgency and scale of the incident. Keywords: Disaster, Mass Casualty Incident, Health Disaster Coordination Center, Disaster Management, Disaster Medicine