Translating between CDA and FHIR

Last updated: Oct 20, 2025
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Clinical Document Architecture (CDA) is a common HL7 standard, based on XML. It’s used for exchanging general clinical documents, including discharge summaries, visit summaries, or other documents with a patient’s history or treatment. Read about CDA.

However, FHIR® is a modern, adaptable, and quick way to exchange general clinical data (learn about the Redox FHIR® API). Sometimes you need data to go back and forth between these two useful healthcare standards. Redox can support you by translating data in either direction with the FHIR® Composition resource.

Who needs to translate between CDA and FHIR®

CDA and FHIR® translation is helpful for these use cases:

  • Providers establishing a new patient’s history before providing treatment.
  • Providers supporting a document-based business process (e.g., generating PDFs).
  • Providers exchanging data over clinical networks, where both FHIR® and CDA are possible.
  • Vendors consuming patient data for service within their app.
  • Payers wanting data for member engagement to recommend preventative care or more cost-effective services.
  • Payers tracking a patient’s treatments for billing purposes (e.g., services included in a hospital stay).

How translation works

Mappings between CDA and FHIR®

CDA to FHIR®

We convert CDA sections into a bundle of the best-fitting FHIR® resources. Check out some examples below.

CDA section

FHIR® resource(s)

Allergies

AllergyIntolerance

Assessment

Health conditions

Problems

Reason for visit

Resolved problems

Condition

Discharge medications

Medications

MedicationRequest and/or MedicationStatement

Encounters

Encounter

Family history

FamilyHistory

Functional status

Observation and SupplyRequest

Health concerns

Condition

Insurances

Coverage

MedicalEquipment

DeviceRequest

Results

DiagnosticReport

Vital signs

Observation

FHIR® to CDA

We can produce an XML document for you based on the FHIR® resources you provide. You can organize your FHIR® resources into these CDA sections.

FHIR® resource

CDA section

AllergyIntolerance

Allergies

Appointment

MedicationRequest

ServiceRequest

SupplyRequest

Plan of treatment

Condition

Problems

DiagnosticReport

Observation

Results

Encounter

Encounters

Immunization

Immunization

MedicationRequest

Medications

Observation

Vital signs

Social history

Procedure

Procedure

Field mapping

Ultimately, Redox converts CDA-specific aspects into FHIR® standards while maintaining accuracy. See some general examples you might come across in most FHIR® resources:

General CDA data

FHIR® field or value

Notes

nullFlavor

data-absent-reason extension

There might be sections of a CDA document that use nullFlavor. Refer to these guides for more details: (a) Section 5.1.5 of this CDA companion guide; or (b) Section 3.6 of this CDA implementation guide.

We convert this to a data absent reason in FHIR®.

Terminology Object IDs (OIDs)

FHIR® terminology

We use the OID from the code system and/or implied value set of a coded value in CDA to look up the appropriate FHIR® Terminology system. Review FHIR® Terminology.

patientRole

Reference to Patient resource

CDAs must include the patient info, which translates into a FHIR® reference to the related Patient resource.

For example, ClinicalDocument.recordTarget.patientRole would translate to AllergyIntolerance.patient.

effectiveTime

Any of these:

(a) date

(b) dateTime

(c) instant

(d) period

(e) onsetDateTime

Different FHIR® resources have different expressions of time, all depending on the context. The effectiveTime converts to the most applicable FHIR® time field.

section.code

General CDA data

The CDA section identifier helps us map the data within that section to the most appropriate FHIR® resource.

For example, if we have section.code=48765-2 then we map the data to the AllergyIntolerance resource.

section.entry.reference

Relevant FHIR® resource

This is a reference to a FHIR® resource in the FHIR® bundle that can be translated to a given CDA section.