Utilization of medical care in Orange County: the effect of implementation of a regional trauma system.

To determine the effect of implementation of a regional trauma system on utilization of medical care we studied ambulance transports, emergency department (ED) visits, and hospital days for trauma and nontrauma patients before and after system implementation. Serious injury affects approximately one of every 1,000 persons each year and accounts for approximately one of every 250 ED visits, one of every 100 hospital days, and one of every 20 ambulance transports. Following system implementation the trauma hospitals experienced insignificant changes in annual percentage of market share of ED visits and hospital days and in annual rate of growth of ED visits and hospital days. We conclude that implementation of a medically directed regional trauma system has resulted in a predictable redistribution of a small number of seriously injured patients, and has not been associated with significant changes in utilization of EDs or hospitals.