During the planning phase of a mass gathering, it is important to organize the most suitable healthcare responses to assure primary, emergency, and major accident care, with the best balance between available resources and costs.

This study tries to develop a Mass-Gathering Event Risk Scoring Model (MGE-RS) to predict Medical Usage Rate (MUR) that can assist emergency medical services providers in planning for mass gatherings across a variety of events and venue types in a metropolitan area.

This study includes 48 mass gatherings in Rome (35 mass gatherings; 2005–2006) and Milan (13 mass gatherings; 2009–2010). All 35 mass gatherings in Rome had > 100,000 attendees (100,000 to 5,000,000), while the 13 mass gatherings in Milan had a median of 100,000 attendees (50,000–200,000). The median patient presentation rate (PPR) was 0.5 patients/1,000 persons: this rate is close to PPRs for mass gatherings reported in the literature (0.5–2.0 patients/1,000 attendees). For each event, the predicted MURs, calculated using the Arbon Model and the MGE-RS Model, were compared with the actual MUR. The MGE-RS scoring model uses a formula that assigns points based on known information (type of event, place, duration, crowd, health system facilities) to predict the risk. The MGE-RS score ranged from 16 to 77. There are five risk levels, each one corresponds to an expected MUR from 1.5 to 45. In the events studied, the predicted MUR calculated with the Arbon model corresponded in 60% of cases (20% under/overestimation); the MGE-RS was in range in 88% of cases (0% underestimated; 12% overestimation).

The MGE-RS seems to be a provider-friendly tool to be used in planning phase, and is able to give an acceptable estimation of the risk level and expected MUR for a mass gathering, without underestimating the estimated MUR during the planning phase.