The purpose of this study was to critically review the provision of medical care at mass gatherings as described in 25 years of case reports. Specifically measured was the relationship between the size of a mass gathering and the frequency of patients seeking medical aid and the effects of certain event characteristics on this relationship.

Data were obtained through a retrospective literature review. Medline and CINHAL computerized databases were searched for English language articles using several keywords: “mass gathering”, “concert”, “festival”, “Olympics”, “crowd”, “riot”, “stadium”, “sports”, “games”, “papal”, and “football”. Only articles containing complete information on the number of spectators, number of patients, type, location, and duration of the mass gathering were included in the primary analysis. As available, additional information was added including the described weather patterns, number of patients transported to a hospital, and number of patients suffering a cardiac arrest. Thirty-five of the approximately 100 articles reviewed, met these criteria.

A Spearman Rank Correlation Coefficient was calculated for number of spectators and patients and a significant relationship was identified (p = 0.0001). Mann-Whitney U-tests indicated that papal masses (p = 0.04), rock concerts (p = 0.005), hot climatic conditions (p = 0.03) and events held in the British Commonwealth (p = 0.03) had a significantly higher frequency of patient visits. Significantly more cardiac arrests occurred at papal masses (p = 0.04) and sporting events (p = 0.0002).

Type of event, country, weather, and the size of the mass gathering had a significant effect on the numbers of spectators seeking medical care. A uniform classification scheme is necessary for future prospective studies of mass gatherings.