MDM Virtualized Endpoint

EAP

If a FHIR Endpoint module is connected to a FHIR Storage (RDBMS) module which is MDM-enabled, it is possible to configure the FHIR Endpoint to be MDM Virtualized.

MDM virtualization attempts to create an endpoint that hides the complexity of the MDM implementation and the linked records, presenting a single unified view of the linked data. A simple example helps to explain this concept:

Suppose you have a FHIR repository with two patients (Patient/A and Patient/B) which are both linked to a golden record (Patient/G).

You then have some Body Height Observations (LOINC code = 8302-2) in the repository, some of which are linked to the first patient and some of which are linked to the second.

In a standard virtualized endpoint:

• a search for Observation?code=http://loinc.org|8302 would return Observations referring to two separate patients. The onus remains on the client to determine that these patients are the same person.
• a search for Observation?subject=Patient/A would return all Observations, and their subject fields will reference Patient/A. The Observations that, at rest, refer to Patient/B are rewritten at egress to look as though they refer to Patient/A.
• a search for Patient/A/$everything will return Observations all referring to Patient/A and Patient/B, although they will all be rewritten to refer to Patient/A.

In a virtualized endpoint, the subject element in each Observation is rewritten before being returned to the client so that it points to the patient included in the search. This means that the client sees all data as belonging to a single person.

Features

With MDM Virtualization enabled:

• Queries are auto-expanded. This means that a search with a patient or subject parameter will be automatically widened to include any linked resources. So, using the example above, a search for Observation?subject=Patient/A would be automatically widened to be processed as 'Observation?subject=Patient/A,Patient/B,Patient/G'.
• References to Patient resources are rewritten to point to the searched patient Patient/A
• If the search result includes the actual patient (e.g. Observation?_include=Observation:subject) the patient is replaced with the searched patient Patient/A.

Architecture

The following diagram shows the architecture of the virtualized endpoint.

Limitations

This setting is only possible when using a FHIR Storage (RDBMS) module.

Search parameter _mdm has no impact if the patient or subject are not part of the query.