The impact of warm weather on mass event medical need: a review of the literature.

Over the last 20 years, interest in medical need at mass events has increased. Many studies have been published identifying the characteristics of such events that significantly impact the number of patients who seek care. Investigators agree that weather is one of the most important variables. We performed a literature search using several biomedical databases (MEDLINE via PubMed, the Cochrane database, BMJ's Clinical Evidence compendium, and Google Scholar) for articles addressing the effect of weather on medical need at mass events. This search resulted in 8 focused articles and several other resources from the reference sections of these publications. We found that the early literature is composed of case reports and predominantly subjective observations concerning the impact of weather on medical need. Most investigators agree upon a positive relationship between heat/humidity and the frequency of patient presentation. More recent authors make attempts at quantifying the relationship and propose prediction models for patient volume and medical personnel requirements. We present an ancestral review of these studies, discuss their results collectively, and propose a simplified algorithm for predicting patient volume at mass events. This review is intended for event planners and mass event emergency medical personnel for planning future events. We also hope to stimulate further study to develop and verify prediction models.