Difference between revisions of "Health Information Exchange"

Revision as of 07:29, 19 November 2010

The totality of a patients’ medical history most often exists in disparate silos (offices, hospitals, clinics, etc.) and often difficult to obtain for physicians. This has been recognized as a major source of inefficiency and a barrier to delivery of quality medical care. To address this problem, a shift in patient data sharing has been developing based on several standards and technologies. The process of health information exchange (HIE) has been described as the “data following the patient”. It is a data-sharing model where the longitudinal health information for a particular patient can be accessed or referenced from a single source and shared securely to an entity also having access to the data. Although health information exchange (HIE) can be considered any process of transmitting health data, the term HIE has been used to describe the infrastructure that is used to electronically exchange patients data between providers. Integrating the healthcare enterprise (IHE) is an initiative by healthcare professionals and industry to improve the way computer systems in healthcare share information. The standard technological infrastructure to support HIE has mainly the work of IHE. Through the development and publication of “integration profiles” IHE has defined the standard processes and technologies needed to support an HIE framework#. The data is typically transmitted electronically in very standard formats using common technologies to register, store, and retrieve the data.

The Document

XML is a standard markup language used to encode data. It is a common language used in web technology and other computing platforms. XML is the language used to encode patient data with the framework of a health information exchange infrastructure. The encoded information is referred to as a “document” and includes both text for human readability as well several vocabulary standards such as SNOMED, LOINC for machine readable structured data. In this way the document can be consumed by an electronic health record or simply rendered by a web browser that is XML capable. Two standards exist for the structural specification of the of the XML document. The first is a lean version of critical patient data called a continuity of care record (CCR). This is an ASTM standard and its purpose was to encode a small set of critical patient data such as demographics, medications, allergies and problems. The second standard is is a derivation of HL7’s common document architecture (CDA) format called the continuity of care document (CCD). This standard is base on CCR structure but adds more complexity and has been designed to carry data sets beyond just the critical data set of the CCR. Although many have looked at these as competing standards, it is more accurate to say they are complementary. The XML document is typically produced by an electronic health record (EMR) from a physician’s office, hospital or a personal health record. The CCD or CCR the only standards of encoding the data.

The Infrastucture

HIEs use web technologies such as TCP/IP for transport between destinations. Once the document is generated it sent to a cross enterprise document-sharing (XDS) environment. There are many vendors in health care who provide HIE infrastucture,. This infrastucture closely adheres to the standard profiles set by IHE. The infrastructure has multiple components but most notably includes: i. The XDS repository(s) are where the documents are stored. These can be centralized or federated. ii. The XDS registry keeps the metadata for each document. In this way a document can be located by querying the registry which links to the actual document in the repository. iii The cross community gateway (XCA) is the profile describing a connection between different HIE environments. Connecting HIEs though XCA technology allows a query to cross into other "connected" HIEs and retrieve patient information located in disparate repositories. In this way several HIEs can deliver federated information about a single patient. iv. The PIX/PDQ defines the way a patient is identified in a registry. First and foremost in any HIE, proper patient identification is paramount to accuracy. The difficulty is that HIEs store documents belonging to one patient but generated from various entities such as different hospitals or clinics. Each entity may not be working with a common patient identifier. Therefore a query needs to match the patient with the correct document using demographic information rather than a master patient index (MPI). The patient identifier cross-reference (PIX) or the patient demographics consumer (PDQ) profiles, are 2 methods for cross-referencing the patient identity attributes.

Securing Information

No explanation of patient data exchange is complete without mentioning security. There are several profiles which define the privacy and security requirements for an HIE infrastructure. The audit trail and node authentication (ATNA) profile address many dimensions of security. It requires data to by encrypted and also outlines a standard for authentication and authorization of data access. Data access and audit trails for reporting each transaction are also outlined in this profile.