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Perspective of an Emergency Physician Group as a Data Provider
for Syndromic Surveillance

Dennis G. Cochrane
Emergency Medical Associates of New Jersey Research Foundation, Morristown, New Jersey; Morristown Memorial Hospital Residency
in Emergency Medicine, Morristown, New Jersey

Corresponding author: Dennis G. Cochrane, Morristown Memorial Hospital Residence in Emergency Medicine, Morristown, NJ 07962. Telephone: 973-971-8919; E-mail:


The need for enhanced biologic surveillance has led to the search for new sources of data. Beginning in September 2001, Emergency Medical Associates (EMA) of New Jersey, an emergency physician group practice, undertook a series of surveillance projects in collaboration with state and federal agencies. This paper examines EMA's motivations and concerns and discusses the collaborative opportunities available to data suppliers for syndromic surveillance. Motivations for supplying data included altruism and public service, previous involvement in terrorism and disaster preparedness, academic research interests, and the opportunity to find added value in the group's existing information systems. Concerns and barriers included cost, maintaining patient confidentiality, and challenges in interacting with the public health community. The extensive and carefully maintained electronic medical record enabled EMA to conduct multiple studies in collaboration with state and federal agencies. The electronic medical record provides useful data that might be more sensitive and specific in detecting outbreaks than the patient-chief--complaint data more commonly used for surveillance. EMA's experience also indicates that opportunities exist for the public health community to work with emergency physicians and emergency physician groups as suppliers of data. Such collaborations not only are useful for syndromic surveillance systems but also can help build relations that might facilitate a response to an actual biologic attack.


The terrorist attacks of September 11, 2001, and the subsequent release through the mail of Bacillus anthracis have increased awareness of the risk for biologic attack. The 2003 severe acute respiratory syndrome (SARS) outbreak also demonstrated the threat of emerging infectious diseases. Certain types of biologic attacks or emerging infectious disease outbreaks might initially present with nonspecific symptoms across a large population. At this stage of disease, a pathologic diagnosis might not be possible, although the symptoms might fall into a definable syndrome. Syndromic surveillance uses available data sources to detect such outbreaks at the earliest possible stage so early action can be taken to mitigate the effects and spread of disease.

Researchers are evaluating the early detection potential of such data sources as pharmacy sales, school and work absenteeism, and emergency department (ED) patient chief complaints. This paper discusses a less commonly used source of ED data --- clinical data from an electronic medical record maintained by an emergency physician group practice. Such data can be made available in real time and can include detailed patient demographics, electronic versions of physicians' notes, physicians' choice of charting templates, laboratory test results, and clinical diagnoses. This paper discusses the motivations and concerns of an emergency medicine group as a data provider and examines opportunities for collaboration between the public health and emergency medical communities. It also describes how these data have been used for research in syndromic surveillance and how data from an electronic medical record might be used for enhanced real-time surveillance.

Practice Setting and Available Data Types

Emergency Medical Associates of New Jersey (EMA) is an emergency physician group practice that is fully owned by the practicing physicians and is constituted as a professional association. EMA contracts with hospitals to provide physician and physician-assistant coverage for 16 EDs in central and southern New Jersey and in New York State, with a combined volume of approximately 2,000 patients/day. The hospitals are a mixture of community hospitals and teaching hospitals, and group members function as faculty for two emergency medicine residencies. The practice receives an estimated one third of all ED visits in the northern half of New Jersey.

Patient visits are recorded by using the group's proprietary clinical software, EDIMS (Emergency Department Information Manager System). The software is integrated with the hospital's patient registration system and stores patient demographic information. It also tracks patient location and status during ED visits and records physicians' notes through a system of charting templates.

All data are uploaded electronically to EMA's central office in Livingston, New Jersey. Reports are generated by a proprietary reporting system, eMars (Emergency Medicine Analysis and Reporting System). These reports are routinely used to monitor billing and ED operations. All data are maintained in an Oracle database. Full clinical data, including physicians' electronic notes, are available from January 1996 to present. Billing data, including International Classification of Diseases, Ninth Revision (ICD-9) billing codes, are available from January 1988 to present.

Surveillance after the September 11, 2001, Terrorist Attacks

Before September 11, 2001, the primary research use of the eMars database had been for epidemiologic studies of emergency medicine conducted by the group's physicians (1--4), who had minimal interest in biologic surveillance. Any interest in disaster management and multiple casualty incidents was concentrated on internal and external disaster plans.

This changed dramatically after the terrorist attacks on the World Trade Center (WTC) in downtown Manhattan on September 11, 2001. On that day, the group's emergency physicians waited at their EDs or at disaster staging sites near the WTC for a potential onslaught of patients that never materialized. Because the threat of an associated biologic attack seemed real, physicians at each ED scrambled to prepare their decontamination equipment and gather information about illnesses that might result from such an attack. They understood that daily life had changed fundamentally and that emergency physicians needed to rethink aspects of disaster preparedness, especially the need to detect and respond to a biologic attack.

Although the WTC attack did not include a release of a biologic agent, it was soon followed by the mailborne release of B. anthracis. Over the following months, a substantial number of patients reported to EDs to "get checked for anthrax." EMA's 16 hospitals treated as many as 62 patients/day (representing 3.5% of all visits groupwide) requesting a test for exposure to B. anthracis and often requesting prophylactic medications. These patients were expecting expert, reliable advice. The ED physician's sense of responsibility was reinforced when an emergency physician was sued for failing to detect one of the first cases of anthrax. Emergency physicians already knew that the ED needed to be prepared to respond to a mass-casualty biologic attack and now realized that they could be held legally liable for not detecting an attack in its earliest phases.

Difficulty of Detecting Changes in Illness Patterns

Surveillance for sentinel cases would rely on astute observation by the ED physician. The New Jersey Department of Health and CDC websites were helpful in establishing diagnostic criteria and reporting mechanisms. The majority of emergency physicians would likely identify a sentinel case of anthrax if the features were typical. However, physicians also realized that in a biologic attack, a person might report initially in a nonspecific way. In addition to looking for a sentinel case, physicians were also advised by CDC to look for "illness patterns and diagnostic clues that might indicate an unusual infectious disease outbreak associated with intentional release of a biologic agent" (5).

The individual emergency physician, working in isolation, might have difficulty detecting a subtle increase in patients reporting with a given nonspecific symptom. Emergency physicians see patients with a diverse group of illnesses whose incidence varies widely. On any given day, emergency physicians expect a greater than usual disease incidence of one or more conditions on the basis of chance alone. For example, at the end of a work shift, a physician might not report seeing three cases of diarrheal illness during that shift even though the average is only one case. A substantial change in case mix over a 24-hour period that would be obvious from examining aggregate data from multiple physicians might appear as random variation to an individual physician seeing only a subset of those patients.

Individual physicians face difficulties in identifying outbreaks. For example, in December 2002, two EMA physicians examined EMA's ED volume data to determine whether the data indicated a seasonal gastroenteritis outbreak, which they believed had started 2 weeks earlier. The data revealed that the outbreak had actually begun 6 weeks earlier (Figure). An ED physician might need to work multiple shifts over a week or more to notice an aberration (e.g., a doubling or tripling of the average number of gastroenteritis cases). The difficulty of outbreak detection is even greater when an individual physician is looking for multiple disease patterns simultaneously.

Syndromic surveillance of aggregate visit data is an important component of preparedness. A biologic attack might cause a sudden increase in the volume of patients with a specific set of symptoms that would be invisible to an individual physician but apparent to analysts using combined data in real time. This might activate heightened surveillance for sentinel cases. In addition, even if an attack was first detected by other means, having rapid access to information about patient volumes could help determine the appropriate response and allocation of resources.

Motivations for Participating in Syndromic Surveillance

EMA was motivated to become involved in syndromic surveillance for multiple reasons. An initial motivator was that syndromic surveillance represented an opportunity for doing research needed to validate its effectiveness. EMA's academic physicians had conducted epidemiologic research by using the billing and clinical databases for >15 years; the same methods could be adapted for research into syndromic surveillance. In particular, EMA's well-maintained and clinically rich database and substantial patient volume would facilitate the study of questions difficult to research in other settings. By collaborating with other agencies, especially public health, EMA physicians might be able to make a contribution to this new field.

The opportunity for public service was another motivator. EMA hospitals cover approximately one third of all ED visits in central and northern New Jersey. Therefore, the group might be able to contribute directly to syndromic surveillance efforts locally. The availability of real-time clinical information from the electronic medical record might offer a unique ability to track and respond to outbreaks.

Another motivator for the group's administrators was that involvement in syndromic surveillance might enhance the group's image in the marketplace. By participating in important public health efforts, EMA's physician group might be perceived as being at the forefront of the specialty in this new area. Such projects might also be a way to demonstrate the added value of the group's information management systems.

Finally, emergency physicians have a personal vested interest in early detection of outbreaks. As illustrated by the 2003 severe acute respiratory syndrome (SARS) epidemic, emergency and hospital personnel can become infected at the initial stages of an outbreak, and health-care personnel can be disproportionately affected overall. Any advance warning could help emergency physicians augment infection-control procedures at the earliest possible time.

Potential Barriers to Participating in Biologic Surveillance

One difficulty with implementing any project in an ED setting is the environment's unpredictable and often chaotic nature. However, the clinical systems in place gather data that can be obtained passively without making further demands on personnel.

Costs were also a concern. To an extent, EMA's robust reporting system, used to produce regular reports for billing, financial management, and operations management and to track physician productivity, could be readily adapted to syndromic surveillance. Because the needed data were already being gathered for other purposes, the expense of generating reports for research would be minimal. The larger expense would come from improving system infrastructure to accommodate the real-time gathering of data. Data are collected daily, but certain data reporting is delayed up to 3 days to ensure its completion on site. Implementing real-time reporting would require system enhancements to enable the necessary fields to be uploaded immediately. Another cost might be the need to reformat data in a standardized format to share with local, state, and national agencies.

Initial costs for generating reports for research purposes were accommodated through the EMA Research Foundation. Improvements in real-time gathering of data were included in an upgrade of EMA's data collection systems. Recently, EMA initiated Internet-based reporting of syndromic trends to EMA physicians as part of a program to facilitate communications and operations within the group using Internet-based technology.

Patient confidentiality and compliance with the Health Insurance Portability and Accountability Act of 1996 (HIPAA) was another concern. Fortunately, EMA's billing and information systems personnel are well-versed in HIPAA requirements and experienced in sharing de-identified subsets of data for billing and reporting purposes. However, large-scale biologic surveillance of the ED population could be perceived as invasive of privacy. This problem might be reduced in a group medical practice in which clinical follow-up and quality control activities are part of everyday operations. Patients are often contacted the day after an ED visit to ensure follow-up with physicians' instructions and to monitor patient outcomes. Biologic surveillance for unusual clusters or trends is a reasonable extension of ongoing medical services. All individual identifying information stays within the practice.

A more substantial barrier is potential resistance within the public health community. Syndromic surveillance is a new field that requires research and validation. Responding to alerts from a syndromic surveillance system might burden the public health infrastructure. Pursuing syndromic surveillance would be futile without the interest of the public health community. Ultimately, EMA identified ample opportunities to collaborate with public health agencies.

Research Projects and Collaborations

EMA's initial research effort into syndromic surveillance was to determine whether the existing database could track known seasonal disease outbreaks. A set of nine ICD-9 code syndrome groupings were developed and used to filter the database. This enabled creation of time-series graphs for each syndrome group over a period of years (6). The data were encouraging in that they depicted seasonal variation for nearly all of the syndrome groups. The seasonal influenza epidemic was identified, as were annual spikes appearing to correlate with the seasonal rotavirus epidemic in children. Seasonal variations in asthma were also identified.

EMA first collaborated with the New York State Department of Health (NYSDOH) to study biologic surveillance methods based on patient chief complaints. By applying methods adapted from the New York City Department of Health and Mental Hygiene to the EMA database, the group was able to demonstrate key seasonal illness patterns, particularly the influenza season, by using a chief-complaint methodology (7). The system's ability to track the influenza season lent credence to its ability to detect other types of outbreaks.

As part of a syndromic surveillance working group, EMA also supplied data for a study of syndromic definitions and ICD-9 code groupings (8). The working group included members of the U.S. Department of Defense's Electronic Surveillance System for the Early Notification of Community-Based Epidemics (ESSENCE) project, CDC, Harvard-Pilgrim Health Care, and EMA. EMA's contribution was to supply ED data that could be used to test different choices of ICD-9 groupings. In addition to providing raw data, participating EMA personnel were able to interpret the data in the ED setting. The data allowed the working group to identify ICD-9 codes commonly used in the ED and differentiate them from codes that are less commonly used but might be better markers of biologic terrorism. This provided a rationale for stratifying codes within a syndrome, so that, if desired, the more common but less specific codes could easily be removed to search for a signal among the less common but more specific codes.

Having studied the existing ICD-9 and chief-complaint methods, EMA and NYSDOH were then able to compare the sensitivity and specificity of the two methods by using a single database (9). This study examined the chief-complaint method for respiratory syndrome by using the ICD-9 method as the criterion standard (9). Two results emerged. First, a substantial difference between the syndrome definitions used for the two methods was noted; although the study initially found poor sensitivity (31%) for chief complaints as compared with ICD-9 codes, sensitivity improved substantially when the methods were adjusted to more closely reflect similar syndrome definitions (sensitivity: 53%). Second, a difference existed between the information captured in the chief complaint and the information captured in the ICD-9 code that could not be resolved. For example, a patient with a chief complaint in the respiratory syndrome (e.g., cough) might easily be assigned an ICD-9 code in a different syndrome (e.g., fever), and vice versa.

These studies were facilitated by the fact that the existing corporate database, originally developed for billing and clinical purposes, was able to provide a large data set with consistent capture of ICD-9 codes and clinical information. Also, the existing data-analysis methods, originally used for corporate analysis, proved a good match for the needs of syndromic surveillance.

Unique data sources within EMA's electronic medical record were also explored. For example, in EMA's system, the physician chooses one of approximately 450 charting templates at the time he or she sees the patient. Thus, the physician's choice of charting template is available in real time before the patient leaves the ED. Because the choice of charting template embodies the physician's clinical judgment, a high level of agreement can exist between the physician's choice of charting template and the final ICD-9 coding of the patient. Comparison of the two methods using the Kappa statistic determined approximately perfect agreement for the asthma, chest pain, and headache filters; excellent agreement for the skin, any gastrointestinal, and diarrhea filters; and moderate agreement for the respiratory and fever filters. (10). These results indicate that the physician's choice of charting template might be useful for real-time biologic surveillance when available in an electronic medical record system.

Ongoing Role for Biologic Surveillance Within EMA's Group Practice

Biologic surveillance reports are now included with other daily, weekly, and monthly reports generated by eMars. These reports provide statistics on the incidence of illness within the practice, categorized by syndrome (e.g., gastrointestinal, respiratory, or febrile illness). The statistics are based on chief-complaints, ICD-9 codes, and physician's choice of charting templates. Reports are circulated to the practice's physicians through group e-mail and posted on the group's website.

Anecdotal feedback from physicians indicates that they appreciate these biologic surveillance reports because they provide early warning of disease outbreaks. For example, by knowing that the influenza season had begun, physicians were able to apprise themselves of the latest recommendations and options for influenza treatment and prophylaxis. A lively discussion ensued about the possible use of neuraminidase inhibitors for patients reporting to the ED with influenza-like symptoms and for their caretakers. In another example, when reports revealed that the annual pediatric gastroenteritis epidemic had begun, EMA's pediatric emergency physicians were able to adjust their treatment of affected children. For children whose pattern of illness matched the pattern expected for the seasonal epidemic, physicians felt more comfortable proceeding with fewer laboratory tests and trusting their clinical impressions. This reduced time, expense, and patient discomfort.


EMA has successfully used its corporate database for collaborative studies with public health agencies. Such efforts represent only a limited portion of similar projects completed or underway in the emergency medicine community, as multiple publications have documented (11--20). Emergency physicians are active in disaster management and terrorism preparedness locally as well as at county, state, and federal levels. Emergency physicians are not only involved in passive surveillance but also have participated in active surveillance (e.g., the drop-in SARS surveillance system implemented recently in Milwaukee [21]).

The partnerships that result from collaborative biologic surveillance projects might be more important than the projects themselves. Because the nature of a future terrorist attack cannot be anticipated, developing collaborative relationships now will enhance the ability of public health authorities to respond flexibly and effectively should such an attack occur.

EMA's experience indicates that opportunities exist for the public health community to work with emergency physician groups as data providers. Such collaborations are useful not only for syndromic surveillance but can also help build relations that might be useful when responding to an actual biologic attack.


The author appreciates the assistance of the New York State Department of Health (Carolyn Stetson, Melissa Mocny, and Trang Nguyen), the New York City Department of Health and Mental Hygiene (Richard Heffernan and Farzad Mostashari), the ESSENCE Project (Julie Pavlin and Virginia Foster), CDC (Dan Sosin and Samuel Groseclose), and the Emergency Medical Associates Research Foundation (John Allegra and Jonathan Rothman). Ed Barthell also provided valuable insight.


  1. Cody RP, Weisel CP, Birnbaum G, Lioy PJ. The effect of ozone associated with summertime photochemical smog on the frequency of asthma visits to hospital emergency departments. Environmental Research 1992;58:184--94.
  2. Allegra JR, Cochrane DG, Biglow R. Monthly, weekly, and daily patterns in the incidence of congestive heart failure. Acad Emerg Med 2001;8:682--5.
  3. Allegra JR, Cochrane DG, Allegra E, Cable G. Calendar patterns in the occurrence of cardiac arrest. Am J Emerg Med 2002;20:513--7.
  4. Alves DW, Allegra JR, Cochrane DG, Cable G. Effect of lunar cycle on temporal variation in cardiopulmonary arrest in seven emergency departments during 11 years. Eur J Emerg Med 2003;10:225--8.
  5. CDC. Recognition of illness associated with the intentional release of a biologic agent. MMWR 2001;50:893--7.
  6. Cochrane D, Allegra J, Rothman J. Real-time biologic surveillance using an existing emergency department electronic medical record database [Abstract]. J Urban Health 2003;80(2 Suppl 1):i120.
  7. Shannon R, Davisson M, Trang N, Stetson C, Jones K. The use of hospital emergency department chief complaint data as a "near" real-time marker for assessing public health risk of infectious disease outbreak [Abstract]. J Urban Health 2003;80(2 Suppl 1):i121.
  8. Foster V. Syndrome definitions for disease associated with critical agents. Presented at the 2003 National Syndromic Surveillance Conference, New York Academy of Medicine, New York, New York, October 24, 2003.
  9. Mocny M, Cochrane DG, Allegra JR, et al. A comparison of two methods for biologic surveillance of respiratory disease in the emergency department: chief complaint versus ICD-9 diagnosis code [Abstract]. Acad Emerg Med 2003;10:513.
  10. Cochrane DG, Allegra JR, Rothman J. Comparison of physician's choice of charting template to ICD-9 codes for biologic surveillance using an emergency department electronic medical records database [Abstract]. Acad Emerg Med 2003;10:525.
  11. Barthell EN, Cordell WH, Moorhead JC, et al. The Frontlines of Medicine Project: a proposal for the standardized communication of emergency department data for public health uses including syndromic surveillance for biological and chemical terrorism. Ann Emerg Med 2002;39:422--9.
  12. Moran GJ, Kyriacoud DN, Newdow MA, Talan D. Emergency department sentinel surveillance for emerging infectious diseases. Ann Emerg Med 1995;26:351--4.
  13. EMERGEncy ID NET Study Group. EMERGEncy ID NET: an emergency department-based emerging infections sentinel network. Ann Emerg Med 1998;32:703--11.
  14. Cordell WH, Overhage JM, Waeckerle J. Strategies for improving information management in emergency medicine to meet clinical, research, and administrative needs. Ann Emerg Med 1998;31:2.
  15. Richards C, Brustein J, Waeckerle J, Hutson HR. Emergency physicians and biological terrorism. Ann Emerg Med 1999;34:183--90.
  16. Hirshon JM. The rationale for developing public health surveillance systems based on emergency department data. Acad Emerg Med 2000;7:1428--32.
  17. Pollock DA, Lowery DW. Emergency medicine and public health: new steps in old directions. Ann Emerg Med: 2001;38:675--84.
  18. Irvin CB, Nouhan PP, Rice K. Syndromic analysis of computerized emergency department patients' chief complaints: an opportunity for bioterrorism and influenza surveillance. Ann. Emerg Med. 2003;41: 447--52.
  19. Suyama J, Sztajnkrycer M, Lindsell C, Otten E, Daniels J, Kressel A. Surveillance of infectious disease occurrences in the community: an analysis of symptom presentation in the emergency department. Acad Emerg Med 2003;10:753--63.
  20. Begier E, Sockwell D, Branch L, et al. The national capitol region's emergency department syndromic surveillance system: do chief complaint and discharge diagnosis yield different results? Emerg Infect Dis 2003;9:393--6.
  21. Foldy SL. Linking better surveillance to better outcomes. MMWR 2004;53(Suppl):12--7.


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