Mass gatherings create difficult environments for which to plan emergency medical responses. The purpose of this study was to identify those variables that are associated with increased medical usage rates (MURs) and certain injury patterns that can be used to facilitate the planning process.

Patient information collected at three types of mass gatherings (professional American football and baseball games and rock concerts) over a three-year period was reviewed retrospectively. Specific variables were abstracted: (1) event type; (2) gender; (3) age; (4) weather; and (5) attendance. All 216 events (total attendance9,708,567) studied were held in the same metropolitan region. All MURs are reported as patients per 10,000 (PPTT).

The 5,899 patient encounters yielded a MUR of 6.1 PPTT. Patient encounters totaled 3,659 for baseball games (4.85 PPTT), 1,204 for football games (6.75 PPTT), and 1,036 for rock concerts (30 PPTT). The MUR for Location A concerts (no mosh pits) was 7.49 PPTT, whereas the MUR for the one Location B concert (with mosh pits) was110 PPTT. The MUR for Location A concerts was higher than for baseball, but not football games (p = 0.005). Gender distribution was equal among patrons seeking medical care. The mean values for patient ages were 29 years at baseball games, 33 years at football games, and 20 years at concerts. The MUR at events held when the apparent temperature was £80°F significantly lower statistically than that at events conducted at temperatures <80°F were (18°C) (4.90 vs. 8.10 PPTT (p = 0.005)). The occurrence of precipitation and increased attendance did not predict an increased MUR. Medical care was sought mostly for minor/basic-level care (84%) and less so for advanced-level care (16%). Medical cases occurred more often atsporting events (69%), and were more common than were cases with traumatic injuries (31%). Concerts with precipitation and rock concerts had a positive association withthe incidence of trauma and the incidence of injuries; whereas age and gender were not associated with medical or traumatic diagnoses.

Event type and apparent temperature were the variables that best predicted MUR as well as specific injury patterns and levels of care.

An extensive review was conducted using the computerized databases Medline and Healthstar from 1977 through May 2002. Articles selected contained information pertaining to mass-gathering variables. These articles were read, abstracted, analyzed, and compiled.

Multiple variables are present during a mass gathering, and they interact in complex and dynamic ways. The interaction of these variables contributes to the number of patients treated at an event (medical usage rate) as well as the observed injury patterns. Important variables include weather, event type, event duration, age, crowd mood and density, attendance, and alcohol and drug use.

Developing an understanding of the variables associated with mass gatherings should be the first step for event planners. After these variables are considered, a thorough needs analysis can be performed and resource allocation can be based on objective data.