An automated tracking system that receives data from all military medical facilities in the Washington, D.C., area could serve as a model for designing a national system for detecting outbreaks of diseases and biological terrorism.
As described in the October issue of the American Journal of Preventive Medicine, the system, known as Electronic Surveillance System for Early Notification of Community-Based Epidemics, or ESSENCE, was created in 1999 in recognition that the D.C. area would be a "high-value target for any terrorist attack and that no such system existed in the national capital area," says Maj. Michael D. Lewis, M.D., M.P.H., of Walter Reed Army Institute of Research.
Subsequent to the events of September 11, 2001, coverage by the system was expanded to over 300 military treatment facilities around the world.
Tests of the preparedness of U.S. public health systems have shown they are often inadequately prepared for deliberate attacks with outbreak-causing diseases, say the army's developers of ESSENCE.
"We believe that ESSENCE is the largest and one of the first U.S. systems to rely on near-real time, patient-level diagnostic data," they note. Data from individual centers generally take less than three days to make it into the system.
The system makes use of readily available data from patients visits to military clinics to classify cases of illness across the region into groups of syndrome categories, such as gastrointestinal, respiratory infection or fever, that allow the system to compare the actual disease incidence against predictions based on historic patterns.
Routinely collected electronic patient information is sent to Military Health System computers that extract and collate information needed to monitor disease levels and identify unusual fluctuations. These data reflect visits by active-duty personnel, spouses, children, retirees and other Military Health System beneficiaries.
"In focusing on rapid identification of space-time-demographic clusters of illness in a community, real-time surveillance based on syndromes or syndrome groups provides a potentially more rapid way to recognize and respond to many natural or unnatural disease outbreak scenarios," Lewis says.
The system works well in part because the developers decided to use only information that clinicians were already recording as part of their routine patient work-up. "It is transparent to the clinician," they say.
The authors note that any system designed to detect disease outbreaks has to balance timeliness of reporting against the quality of the data. It should be sensitive enough to detect significant clusters of diseases while not being so sensitive that it triggers a lot of false alarms.
They predict that systems based solely on ambulatory data will likely never be sensitive enough to detect outbreaks of disease that occur in very small numbers, such as West Nile virus, or even the few people affected by anthrax exposure last year.
"The key piece to any system, however, is not 100 percent reliance on the technology to give the correct answer. There can be no substitute for human interfacing to make a good clinical judgement based on gathering all information available," they note.
They also note that because the Department of Defense has a networked, globally standardized, medical information system that facilitated the implementation of ESSENCE. By comparison, clinicians who work in civilian clinics do not have the same standardized requirements for collecting patient data. However, there are other methods of data collection that are relatively uniform across medical professionals outside the military and government that have the potential to be adapted to a similar surveillance system.
FOR MORE INFORMATION
Health Behavior News Service: (202) 387-2829 or www.hbns.org.
Interviews: Contact Michael Lewis at the Mayflower Hotel, Washington, D.C., at (202) 347-3000 from Sept. 20-22, or at the Sheraton Hotel and Towers in New York City at (212) 581-1000 from Sept. 22-25.
American Journal of Preventive Medicine: Contact the editorial office at (619) 594-7344.
Journal
American Journal of Preventive Medicine