The chief complaints recorded at the time of registration are among the earliest data available electronically from a patient's interaction with the healthcare system. They are typically recorded before a doctor sees a patient. If the ED or a clinic is busy, many hours may pass before a registered patient is seen by a clinician.
The time latency between recording of a chief complaint and its availability to a biosurveillance organization can range from seconds to days, depending on whether the data collection system utilizes the HL7-messaging capability of a healthcare system for real-time communication or batch transfer of files (Figure 23.2). Hospitals are frequently capable of real-time transmission whereas office practices are not—unless they are associated with a larger organization (e.g., the Veterans Administration, U.S. military, or a large healthcare system).
Real-time transmission is possible when a healthcare system has a pre-existing Health Level 7 (HL7) messaging capability. Several publications describe the technical approach to HL7-based data collection and chief-complaint processing (Tsui et al., 2002, 2003, Gesteland et al., 2002, 2003, Olszewski, 2003a). Briefly, when a patient registers for care at an ED, a triage nurse or registration clerk enters the chief complaint into a registration system. This step is part of normal workflow in many U.S. hospitals (Travers et al., 2003). The registration system almost always transmits chief-complaints in the form of HL7 messages (Tsui et al., 2003) to an HL7-message router located in the healthcare system. To transmit these data to a biosurveillance organization, the healthcare system would configure the HL7-message router to de-identify these messages and transmit them via the Internet to a biosurveillance organization as they are received from the registration system. This configuration process is a native capability of commercial HL7-message routers and it is a routine task for an HL7 engineer or other information technology staff working in or for a healthcare system.
Batch transfer can either be automatic or manual. Automatic means that a computer program periodically queries the registration computer (or other system in which the chief complaint data are stored) for recent registrations, writes a file, and transmits the file to the biosurveillance organization via
4 Febrile syndromes provide a more realistic and common example of this problem. Many of the infectious diseases that represent threats to the public's health produce a febrile response in affected individuals early in the course of illness. From an epidemiological standpoint, monitoring febrile syndromes, such as Febrile Respiratory, will increase the chance that a positive patient actually has an infectious disease and will decrease the number of false positives. However, chief complaints—being terse-rarely describe both a syndromic symptom and fever. Of 610 patients who actually had febrile syndromes (Febrile Respiratory, Febrile GI, Febrile Neurological, Febrile Hemorrhagic, or Febrile Rash), only 5% of the chief complaints described both fever and the symptoms related to the organ (Chapman and Dowling, 2005).
figure 23.2 Comparison of time latencies of real-time and batch feeds.The negative time latencies associated with the real-time feed are due to slight clock differences between the biosurveillance system and the ED registration system.
Minutes Hours figure 23.2 Comparison of time latencies of real-time and batch feeds.The negative time latencies associated with the real-time feed are due to slight clock differences between the biosurveillance system and the ED registration system.
the Internet. The transmission may use a secure file transfer protocol, non secure file transfer protocol, a web transfer protocol, or PHIN MS.5 Manual means that someone working in the healthcare system must run a query and attached the results of the query to an email to the biosurveillance organization, or upload the file to a computer in the biosurveillance organization. In the past, manual data transfer often involved faxing of paper log files.
Tsui et al. (2005) studied the time latencies, data loss, and reliability associated with real-time HL7 feeds and batch feeds. Figure 23.3 compares the distribution of time delays between the time that a chief complaint was recorded during registration and receipt of that chief complaint by a biosurveillance system. The median time delay for a real-time feed was 0.033 hours and for batch was 23.95 hours.
The proportion of U.S. hospitals that are capable of sending a real-time HL7 feed appears to be approximately 84% based on our experience. Table 23.5 summarizes our experience with hospitals in the United States, suggesting that many hospitals have this capability.
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