Prehospital intervention probability score: a novel method for determining necessity of emergency medical service units

Contrary to current practice patterns of placing paramedic units in regions of greatest population density, we established a formula based on population vs intervention probability. We found the actual numbers of interventions performed are not dependent solely on population size but also are affected by the age of the population being served. This is particularly relevant to growing elderly communities. This determination will aid in the disbursement of limited prehospital resources in regions by improving availability of EMS personnel.