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http://www.nytimes.com/2002/07/04/technology/circuits/04SICK.html

Tracking an Outbreak Minute by Minute

By CATHERINE GREENMAN

OMPUTER networks have been used for years by public health officials to monitor outbreaks of disease. Typically, the networks compile a database of reports about sick patients from doctors or other health care workers and look for patterns of illness or symptoms. But the reporting and compiling can take a day or more, delaying detection of an outbreak.

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Even before the anthrax attacks in the United States last fall, public health experts had recognized a need for more rapid surveillance and detection, given that an outbreak may involve deliberate and widespread attempts to infect rather than the natural spread of contagion. Several universities and hospitals are developing systems to collect and analyze disease data immediately — as soon as a patient is admitted to a hospital emergency room, for example.

One such program, called Real-Time Outbreak and Disease Surveillance, or RODS, is being developed at the Center for Biomedical Informatics at the University of Pittsburgh. Since October, the program, financed primarily by the National Library of Medicine, has been receiving data about patients through a private computer network from 15 hospital emergency departments in Western Pennsylvania as soon as the patients are admitted.

The information includes the chief complaint a patient gives to emergency room administrators, like respiratory problems, rashes or diarrhea. The system also notes the patient's age, time and date of visit, gender, and ZIP code. This information is kept separate from the patient's name, address and Social Security number to protect privacy.

The system compares new reports with those in its database, looking for similarities. In addition, the RODS project uses geographic information systems software that maps the data to reveal any geographical patterns behind the surveillance information.

"Our goal is to be able to analyze patterns and ask whether there is something unusual compared to the usual," said Dr. Michael Wagner, assistant professor of medicine at the University of Pittsburgh and director of the RODS Laboratory and the Biomedical Security Institute in Pittsburgh.

Because it focuses on symptoms of patients seeking emergency care, delays in the detection of outbreaks could be cut significantly.

"A lot of places receive data in batch mode at midnight," Dr. Wagner said. "This can mean delays in detection of up to 24 hours."

The idea, he said, is that "if 10 people show up with diarrhea in the middle of the night, it's going to be detected at 3 a.m. rather than at midnight the next night." If those people are the first of many victims of a bioterrorism incident, one that will require large amounts of resources like medicine to fight, "those hours are going to make a difference," Dr. Wagner said.

During the Winter Olympics in Salt Lake City in February, RODS linked to about 30 area hospitals and walk-in clinics. Although there were no incidents of bioterrorism during the games, the system did detect an influenza outbreak based on the number of patients who showed up with respiratory complaints.

Ideally, as the RODS system evolves, it would find ways to link to other sources of data.

"There's a torrent of information being collected routinely in real time," Dr. Wagner said. "Over-the-counter sales of pharmaceuticals contain information that's very relevant to outbreaks of disease. Our goals include building a thin layer of data collection infrastructure on top of the existing data collection systems of health care and other industries."

Another real-time disease surveillance program, the Children's Hospital Project in Boston, monitors its own complaint data and data from another Boston hospital, Beth Israel Deaconess Medical Center. Several other area hospitals have agreed to collaborate over the next year. Doctors involved in the project are particularly interested in exploring whether changes in patient behavior can be interpreted as early indicators of disease outbreaks.

"When people get sick, their behavior changes, and some of these changes will influence their use of the health care system," said Dr. Kenneth Mandl, attending physician in pediatric emergency medicine at Children's Hospital in Boston. He is also a principal investigator of the Children's Hospital Project, which is financed by the federal Department of Health and Human Services.

He said that the group was looking for "signature patterns" in sets of data from emergency departments to detect small and large surges in certain kinds of visits.

If anthrax was released into a ventilation system in a school, for example, Dr. Mandl and his staff would look for increases in numbers of children showing up at hospitals with flulike symptoms over the course of each day, in addition to clusters of children coming in who lived near one another.

The trick is having a foundation of data about normal behavior patterns for comparison, Dr. Mandl said. The Boston project is using a database with information on hundreds of thousands of patients who have been seen in the emergency department at Children's Hospital over the last eight years.

Whether the goal is to get immediate access to information or not, disease surveillance systems face many hurdles, most notably the cooperation of doctors and hospitals in making patient information available in standardized form. Virtually everyone in the field agrees on the importance of developing systems that do not require any extra work from hospital personnel.

"Doctors aren't very compliant about reporting, so the surveillance systems that rely on that kind of effort tend not to work very well," Dr. Mandl said.

Others question whether patients' complaints are the most accurate way of gauging potential threats, or whether a doctors' diagnoses or requests for laboratory tests are a better indicator.

"We think the clinician is going to give us a better picture of a potential syndrome rather than a patient's self-report," said Dr. Jeffrey Duchin, who oversees a system in the Seattle area that monitors patient discharge diagnoses in 12 emergency rooms.

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