US Core Implementation Guide
4.2.0 - CI Build

US Core Implementation Guide, published by HL7 International - Cross-Group Projects. This is not an authorized publication; it is the continuous build for version 4.2.0). This version is based on the current content of and changes regularly. See the Directory of published versions

DSTU2 to R4 Conversion


There are several consideration for the user and developer experience when transitioning from FHIR DSTU2 to FHIR R4. To ensure a smoother upgrade path the following the guidance is provided.

Endpoint Discoverability

A server may make explicit which version of Argo/US Core on their FHIR endpoint (e.g., “DSTU2” or “R4” path component or separate files based on version). However best practice is to inspect the endpoint metadata on each endpoint to discover the information about a server’s capabilities including the FHIR version and the US Core Profile version that is supported:

GET [base]/metadata{?mode=[mode]} {&_format=[mime-type]}

No Guarantee that Resource IDs are Preserved

In some FHIR servers the identifier of the underlying clinical data is not maintained across FHIR versions. Client applications must plan on deduplication methods that don’t rely on a common identifier across FHIR versions.

  • Servers SHOULD maintain a stable common identifier for a resource across versions.

Expectation that DSTU2 Data is Preserved in R4

In an upgraded R4 endpoint any data in DSTU2 should be in R4. However, not all data in R4 may be available in DSTU2 because some profiles and data classes like Clinical Notes and pediatric observations are not part of DSTU2.

  • The FHIR RESTful resource types supported in a DSTU2 implementation SHALL be supported in a R4 implementation
    • Exceptions
      • MedicationStatement MAY be deprecated and the data SHALL be mapped to MedicationRequest.
      • Care teams as represented by CarePlan in DSTU2 SHALL be replaced by and the data mapped to CareTeam in R4
  • Servers SHALL make available the same information in DSTU2 and R4 where the more recent standard allows. (e.g., patient Rhonda Jones is available on both)
    • Exceptions
      • MedicationStatement data mapped to MedicationRequest
      • care teams as represented by CarePlan SHALL be mapped to CareTeam in R4
  • Data SHALL not be degraded between versions.
  • When updating between versions, clients should consider the impact of any changes to data visualization on the usability for the end user and the maintenance of data integrity.

Authorization Across Versions

  • Separate authorization is required
    • There is no expectation that DSTU2 authorizations will work on R4 endpoints and reauthorization is required when migrating between versions.
      • Maintaining the same auth server for both endpoints so that the refresh token is valid for both DSTU2 the R4 endpoint as well may be possible but not in scope.
  • The new endpoint will bring additional/changed resource types and added scopes

    The table below summarizes the different profiles and resource types between DSTU2 and R4:

DSTU2 Profile Equivalent R4 Profile Notes
Argonaut AllergyIntolerance Profile US Core AllergyIntolerance Profile  
Argonaut CarePlan Profile US Core CarePlan Profile Resource type changed from CarePlan in DSTU2 to CareTeam in R4
Argonaut CareTeam Profile US Core CareTeam Profile  
Argonaut Condition Profile US Core Condition Profile  
Argonaut Device Profile US Core Implantable Device Profile  
Argonaut DiagnosticReport Profile US Core DiagnosticReport Profile for Laboratory Results Reporting  
Argonaut DocumentReference Profile US Core DocumentReference Profile  
Argonaut Goal Profile US Core Goal Profile  
Argonaut Immunization Profile US Core Immunization Profile  
Argonaut Medication Profile US Core Medication Profile  
Argonaut MedicationOrder Profile US Core MedicationRequest Profile  
Argonaut MedicationStatement Profile   US Core MedicationStatement Profile not defined in R4, Map DSTU2 data to MedicationRequest
Argonaut Observation Results Profile US Core Laboratory Result Observation Profile  
Argonaut Patient Profile US Core Patient Profile  
Argonaut Procedure Profile US Core Procedure Profile  
Argonaut Smoking Status Observation Profile US Core Smoking Status Observation Profile  
Argonaut Vital Signs Observation Profile FHIR Vital Signs Profile The FHIR Vital Signs Profile is published in the FHIR specification
- US Core DiagnosticReport Profile for Report and Note exchange New Profile in R4
- US Core Encounter Profile New Profile in R4
- US Core Location Profile New Profile in R4
- US Core Organization Profile New Profile in R4
- US Core Pediatric BMI for Age Observation Profile New Profile in R4 based on the FHIR Vital Signs Profile
- US Core Pediatric Head Occipital-frontal Circumference Percentile Profile New Profile in R4 based on the FHIR Vital Signs Profile
- US Core Pediatric Weight for Height Observation Profile New Profile in R4 based on the FHIR Vital Signs Profile
- US Core Practitioner Profile New Profile in R4
- US Core PractitionerRole Profile New Profile in R4
- US Core Provenance Profile New Profile in R4
- US Core Pulse Oximetry Profile New Profile in R4 based on the FHIR Vital Signs Profile