The model, a Trauma Resource Allocation Model for Ambulances and Hospitals (TRAMAH), assists trauma system planners in better locating their resources with respect to spatial needs and response times. It employs linear programming, a technique commonly used in operations research, to simulate different positioning combinations of trauma centers and helicopters.
Trauma systems are designed to offer much-needed medical treatment to severely injured people in a timely way. The TRAMAH researchers used Maryland, a state that pioneered the trauma systems concept, as a test region. The state has nine trauma centers and eight aeromedical depot sites.
Access Improves To Over 99%
The researchers analyzed the response to 26,774 severe injuries in Maryland between 1992 and 1994. During this period, 94.8% of severely injured residents had access to trauma system resources within 30 minutes and 70.3% had access within 15 minutes.
In contrast, for the same number of resources as the existing Maryland Trauma System, TRAMAH simulated access within 30 minutes for 99.97% - a 5% increase to nearly 100%. Consideration of such simulations could offer life-saving trauma care to hundreds more severely injured people every year.
More Ways To Improve Access
The researchers considered improving access by separately changing the number of trauma centers or the number of helicopter depots rather than considering both types of resources in tandem. The results were especially interesting for Maryland, a state with an already well-developed trauma system.
Holding in place the nine trauma centers of the existing system, approximately the same percent coverage as the existing system - 70.3% - potentially could be achieved within 15 minutes by optimally locating significantly fewer helicopter depots, a benefit to taxpayers. If all eight aeromedical depots were retained and optimally located, the response time to severe injuries within 15 minutes would improve by 15.1%, to 85.4%.
The researchers also considered a different variation, holding in place the eight aeromedical depots of the existing system. Removal and optimal replacement of single trauma center sites increased coverage within 15 minutes by an average of 4.2%. The optimal replacement of any one of the nine trauma centers in the existing system would therefore provide trauma system access to hundreds more severely injured people each year.
Background
In the past decade, say the authors, substantial progress has been made in developing guidelines for the location of trauma care resources. But, they say, political concerns and historical patterns have interfered. In response, the researchers used operations research to bolster trauma systems design.
TRAMAH was applied and tested from two different perspectives. The first assumed that no existing trauma care resources were present. Resources were thus located as if the state were a "clean slate." The second perspective began with the existing configuration of trauma resources and made incremental changes to this configuration. The two perspectives show TRAMAH's flexible application to both highly and less developed trauma systems.
The authors, nonetheless, caution that this first application was not necessarily meant to be an evaluation of Maryland. Rather, it was more of a probationary demonstration of TRAMAH's adaptability to any state. Further research, including the incorporation of Global Positioning Systems and more specific information on hospital and helicopter costs and service capacities, is underway to enhance the application of TRAMAH.
The study was conducted by Dr. Charles C. Branas, University of California, Berkeley; Dr. Ellen Mackenzie, Johns Hopkins University; and Dr. Charles ReVelle, Johns Hopkins University. It was supported by a grant from the Agency for Health Care Policy and Research.
Operations Research Convention in Montreal
The paper is being presented during a convention of INFORMS and CORS in Montreal. It takes place at the Montréal Bonaventure Hilton and Queen Elizabeth Hotel from Sunday, April 26 to Wednesday, April 29.
The convention will include sessions on topics applied to a wide number of fields, including aviation, health care, information technology, the Internet, energy, marketing, package delivery, pharmaceuticals, securities, and telecommunications. More than 1,600 papers are scheduled to be delivered at the four-day conference.
Operations researchers and management scientists are little known but indispensable experts who use science to improve decision-making, management, and operations. They work throughout business, government, and academia. Additional information on the conference, including a full list of workshops, is available at http://www.informs.org/Conf/Montreal98/
The Institute for Operations Research and the Management Sciences (INFORMS) is an international scientific society with 12,000 members, including Nobel Prize laureates, dedicated to applying scientific methods to help improve decision-making, management, and operations. Members of INFORMS work primarily in business, government, and academia. They are represented in fields as diverse as airlines, health care, law enforcement, the military, the stock market, and telecommunications.
The Canadian Operations Research Society (CORS), founded in 1958, works to advance the theory and practice of operations research. Its primary purpose is to stimulate and promote contacts between those interested in operations research. CORS members are employed across Canada in various industries, government, and academia.