for decision support for patients

LTC indicates long-term care facility; HMO, health maintenance organization; HS, hospital system; ADT, admission discharge and transfer; ?, unknown; —, not applicable; CPT, Current Procedural Terminology; ICD-9, International Classification of Diseases 9th edition. Adapted from Agency for Healthcare Research and Quality report.

query message type.4 For these reasons, HL7 messaging is a core element of emerging biosurveillance IT standards, as we discuss in Chapter 32. It is worthwhile to point out that HL7 defines a communications protocol at the application layer and does not address the transport layer (e.g., TCP/IP, HTTP, RS-232). Therefore, it is possible for two systems to speak HL7 at the application layer but still not be able to physically communicate.

Healthcare organizations that own multiple hospitals and physician practices may use an HL7-message router to integrate the data systems of these geographically diverse practices. In these settings, the HL7-message router represents a single point of integration between a biosurveillance organization and scores of hospitals. For example, when the Utah Department of Health deployed the RODS system for the 2002 Winter Olympics, it created a single connection to the Intermountain Healthcare System HL7-message router, enabling it to collect registration data from nine emergency departments and 19 acute care facilities (e.g., urgent cares, instacares and now cares). It created a second connection to the University of Utah HL7-message router to add one emergency department, one urgent care, and the polyclinic located in the Olympic Village to the biosurveillance system (Gesteland et al., 2002, 2003,Tsui et al., 2002).

Regarding data exchange with a hospital or other large healthcare organization, key questions to ask about HL7-message routers are as follows: Do you have an HL7-message router (you may have to ask the IT person and remember that it is also called an integration engine)? Which information systems send messages to it? How many hospitals and office practices are connected to it? Do you maintain it, or do you outsource its maintenance? What is your minimum lower level protocol (e.g., TCP/IP, HTTP, RS-232) for HL7 messages if you have an HL7-message router? Note that these and questions that we suggest for other information systems may best be answered by the healthcare organization's IT staff, and in many instances, they are best answered by the organization's HIS vendor.

4 There are multiple HL7 query message types such as QBPAQ21 (query for person demographics), QRYAQ28 (query for pharmacy dispense information), VXQAV01 (query for vaccination record).

Registration Pathology Laboratory Point-of-care {ED} Point-of-care (ICU) Radiology Data warehouse

FIGURE 6.1 Representative information system architecture of a modern healthcare system. A healthcare system may also create direct connections between systems such as the laboratory information system and a point-of-care system (not shown).

6.2. Registration Systems

Clerical staff in emergency departments (and other medical facilities) register patients electronically at the time that they present for care. Electronic patient registration is nearly ubiquitous in the United States, especially in emergency departments and hospital-based or hospital-associated office practices and large health maintenance organizations. The registration clerk enters the reason for visit (also called the chief complaint) at the time of registration, along with the patient's age, gender, and home address. Syndromic surveillance systems analyze de-identified versions of these data (without patient name and with home address information limited to zip code) (Espino and Wagner, 2001; Lober et al., 2001;Tsui et al., 2001;Wagner et al., 2001).

The main advantage of registration data for biosurveillance is its widespread availability in the United States and inherent timeliness. If a healthcare organization has an HL7-message router, chances are good that the registration system sends messages to it and that it can de-identify and forward these data to a biosurveillance organization in real time.

6.3. Billing Systems

Billing was one of the first hospital functions to be computerized. Billing systems contain information about diagnoses and tests that were performed (but not the results). Third-party payers such as insurance companies require that a hospital encode this information by using either Current Procedural Terminology (CPT) or International Classification of Diseases, 9th edition (ICD-9) codes, a process that in many healthcare settings is done manually by professional coders. This process may introduce a several-day delay between the time the patient is seen and the diagnoses are available in a billing system. Billing data are often routed through an HL7-message router, and the combination of the widespread availability of both billing systems and HL7-message routers makes billing data highly available for biosurveillance. We note that third-party payers consolidate billing data from many hospitals and healthcare providers. Because the number of payers is typically smaller than is the number of hospitals and healthcare providers in a community, payers are a potentially more efficient source of billing data.

6.4. Laboratory Information Systems

A laboratory information system receives and stores requests for tests, and results are entered by laboratory technicians or directly from laboratory instruments (e.g., via the ASTM E-1381 protocol Specification for Low Level Protocol to Transfer Messages between Clinical Laboratory Instruments and Computer Systems). Results of tests are available via paper reports and electronic interfaces, both to human users and to other information systems such as a POC system (described below).

Laboratory information systems in hospitals, the animal health system, governmental public health, and commercial free-standing laboratories are virtually identical. For this reason, we devote Chapter 8 to the role of laboratories and networks of laboratories in biosurveillance.

Briefly, laboratories perform tests that include all types of cell counts, analytical chemistry, drug and toxin screening, and detection of microbes. The results of these tests are important to biosurveillance of virtually every conceivable biological agent. Fortunately, the vast majority of clinical laboratories in the United States are highly automated, using computers to perform tests, store results, and communicate results. Test results are generally available electronically very soon after the tests are performed. Results are available not only directly from the laboratory information system but may also be transmitted to an HL7-message router and to an enterprise data warehouse or a POC system (described below). There are many examples of hospitals that send laboratory data electronically to health departments, although these hospitals represent but a tiny fraction of the approximately 5,000 hospitals in the United States (Effler et al., 1999; Overhage et al., 2001; Hoffman et al., 2003).

Not only are the results of laboratory tests of value to biosurveillance, but so may be the mere fact that a particular test was ordered. The type of test ordered provides a clue to the clinician's diagnostic thinking about the nature of the illness in a patient, and it may be available well in advance of the result of the test, possibly within minutes or hours of a physician first seeing a patient.

At present, unfortunately, obtaining laboratory results from hospitals requires extensive custom interface development to translate and reformat data. Many hospitals use proprietary coding schemes to represent the names of tests and the results of tests. For example, the organism Bacillus anthracis may be called ANTX in one institution and BANTHRACIS in another. Dr. Clem McDonald recognized this importance of

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