To describe the epidemiological profile of multiple casualty incidents (MCI) and contribute to the better understanding of their impacts in Northern Spain.

Retrospective, population-based observational study of MCI between 2014 and 2020 in 5 autonomous communities (Aragón, Castilla y León, Galicia, the Basque Country and Principado de Asturias) that participated in the MCI Database of Northern Spain. Inclusion criteria was any incident with 4 or more patients needing ambulance mobilization. A total of 54 variables were collected. This study presents the most relevant results.

There were 253 MCI. Of these, 79.8% were road traffic accidents, 12.3% fires or explosions, 2.0% poisonings and 5.9% defined as others. Monthly average was 2.9 (SD = 0.35; EEM = 15.90), average of victims by MCI was 6.8 (CI95% 6.16 - 7.60). There were significantly (P < 0.05) more victims in 3 types of MCI (fires, poisonings, and others). We saw 37.7% of MCI involved 4 victims, 18.8% 5 victims, and 37.9% more than 5. Mean response time was 30.8 minutes (95% CI 28.6 - 33.1), longer in maritime incidents. A total of 67% (95% CI 64.5 - 69.5) of victims were mild.

Road traffic accidents are the most frequent MCI and minor injuries predominate. More than 50% of the MCI have 5 or fewer patients. Fires had significantly more mild patients and significantly more resources deployed. Maritime incidents had a significantly longer response time.

Multiple casualty incidents (MCI) are infrequent events for medical systems. This renders audit and quality improvement of the medical responses difficult. Quality tools and use of such tools for improvement is necessary to ensure that the design of medical systems facilitates the best possible response to MCI.

To describe the utility of incident reporting as a quality monitoring and improvement tool during the deployment of medical teams for mass gatherings and multiple casualty incidents.

Voluntary and confidential reporting of incidents was provided by members of the disaster medical response teams during the period of disaster medical team deployment for the 2000 Sydney Olympic Games. Qualitative evaluations were conducted of reported incidents. The main outcome measures included the nature of incident and associated contributing factors, minimization factors, harm potential, and comparison with the post-deployment, cold debriefings.

A total of 53 incidents were reported. Management-based decisions, poor or non-existent protocols, and equipment and communicationrelated issues were the principal contributing factors. Eighty nine percent of the incidents were considered preventable. A potential for harm to patients and/or team members was documented in 58% of reports, of which 76% were likely to cause at least significant harm. Of equipment incidents, personal protective equipment (33%), medical equipment (27%), provision of equipment (22%), and communication equipment (17%) predominated. Personal protective equipment (50%) was reported as the most frequent occupational health and safety incident followed by fatigue (25%). Predeployment planning was the most important factor for future incident impact minimization.

Incident monitoring was efficacious as a quality tool in identifying incident contributing factors. Incident monitoring allowed for greater systems evaluation. Further evaluation of this quality tool within different disaster settings is required.