Source System Identification
HIEBus must be able to distinguish between different source systems and identify when messages coming through different channels or interfaces originate from the same source system. There are two primary reasons for this requirement:
- Record authority. It must know which system generated the patient record identifier. Record authority in HIEBus is analogous to an Assigning Authority.
- Term namespace. It must know which system produced the codes in use throughout the message. Term namespace in HIEBus is analogous to a code system that defines a set of codes and their descriptions. Codes are expected to be unique within a given code system.
There are two main ways HIEBus can be configured to identify the source system:
- Fixed. All messages received by the interface originate from the same system. While the system that generated patient record identifiers and that which produced the codes need not be the same system, this mode enables a single record authority and a single term namespace to be fixed for all messages received on the interface.
- Dynamic. This method allows the record authority code and term namespace code to be generated based on information present in the message. There is no requirement that the record authority and term namespace codes derive from the same data element within the message. For e.g. the term namespace might be set based on MSH-4 and the record authority might be derived based on PID-3.4. If record authorities are being dynamically determined, then a whitelist of allowed record authorities is required; messages with authorities not on the whitelist will be rejected.
To assist in deciding which mode is right for your situation, the following table is provided:
| Scenario | Recommendation |
|---|---|
| All messages received by the interface originate from the same system. | Fixed |
| The interface is an aggregation of 2 or 3 source feeds. | Dynamic |
| The interface is primarily from a single facility, but there are some satellite clinics that also combine on the feed. | Dynamic |
| The feed comes from an HIE that aggregates messages from multiple sources, the set of which may change at any time. The HIE has its own patient matching algorithm to ensure that it forwards only the appropriate messages, and the HIE sends its own patient identifier with the message. | Dynamic, fixed record authority, term namespace determined by MSH-4. |
| The feed comes from an HIE that aggregates messages from multiple sources, the set of which may change at any time. The messages are forwarded by the HIE as-is, with minimal modification, and patients are identified by the MRN generated by the original system. | Dynamic, record authority and term namespace determined by MSH-4. |
| The feed comes from a source that aggregates messages from multiple HIEs that themselves aggregate messages from multiple originating facilities. The messages are forwarded by this aggregator largely as-is, with minimal modification, and patients are identified by the patient identifier generated by the intermediate HIEs. | Dynamic, record authority and term namespace determined by different data elements. |
See the sections on Record Authority and Term Namespace for additional information as to how these concepts are identified and used.
