This page is part of the C-CDA on FHIR Implementation Guide (v1.2.0: STU 1) based on FHIR (HL7® FHIR® Standard) R4. This is the current published version. For a full list of available versions, see the Directory of published versions

C-CDA to FHIR Medications

This page provides a mapping from CDA to FHIR. For the FHIR to CDA mapping, please refer to Medications FHIR → CDA. For guidance on how to read the table below, see Reading the C-CDA ↔ FHIR Mapping Pages

Medication Timing and Frequency

C-CDA represents both timing (start date / end date) and frequency (when and how often to take) using <effectiveTime> elements. The first (represented in XPath as /effectiveTime[1]) represents the timing. If it contains <low> and/or <high> timestamps, this represents the .timing.repeat.boundsPeriod information of MedicationRequest.dosageInstruction. If, instead, the first effectiveTime only contains a single @value attribute, it represents a .timing.event dateTime value.

The second <effectiveTime> represents the frequency and contains the attribute @operator="A" to indicate it is an intersection with the first effectiveTime. It must also have an @xsi:type attribute which identifies the type of frequency as PIVL_TS (Periodic Interval) or EIVL_TS (Episodic Interval). PIVL_TS is the most common and represents a frequency corresponding to .timing.repeat.frequency / .timing.repeat.period / .timing.repeat.periodUnit. These relationship of three fields is described in FHIR: “Event occurs frequency times per period”. For example: “Every 8 hours” would become 1 / 8 / h (one time every eight hours), while “TID” would become 3 / 1 / d (three times every one day).

EIVL_TS represents an event-based frequency, such as “1 hour after meal”. The CDA <event code="xx"> corresponds to FHIR’s .timing.when and the optional <offset> corresponds to .timing.offset.

The C-CDA Example Search site maintains a document of Common Medication Frequencies which can be cross-referenced with a similar table in FHIR’s Timing Data Type to properly map CDA frequencies to FHIR timing values.

C-CDA to FHIR

C-CDA¹ Medication Activity substanceAdministration	FHIR MedicationRequest	Transform Steps
/@negationInd=”true”	set .doNotPerform=true
@moodCode	.intent	CDA coding ↔ FHIR CodeableConcept Mood to intent
/id	.identifier	CDA id ↔ FHIR identifier
/statusCode	.status	Pay attention to the definitions of active and completed in the FHIR medicationrequest-status code system. C-CDA may list a medication state as “completed” (i.e. the prescription writing has been completed), but containing dates in the future. This may more align with a FHIR status of “active” than “completed” which indicates all actions implied by the prescription have been completed CDA statusCode → FHIR status
/effectiveTime[1]/@value	.dosageInstruction.timing.event	Constraint: Use this when effectiveTime@value is populated CDA ↔ FHIR Time/Dates
/effectiveTime[1]/low	.dosageInstruction.timing.repeat.boundsPeriod.start	Constraint: Use this when effectiveTime/@value is not populated CDA ↔ FHIR Time/Dates
/effectiveTime[1]/high	.dosageInstruction.timing.repeat.boundsPeriod.end	Constraint: Use this when effectiveTime/@value is not populated CDA ↔ FHIR Time/Dates
Periodic Frequency /effectiveTime[operator=”A” and xsi:type=”PIVL_TS”] …/@institutionSpecified …/period/@value …/period/@unit	.dosageInstruction.timing.repeat.frequency .dosageInstruction.timing.repeat.period .dosageInstruction.timing.repeat.periodUnit	Compare: C-CDA Common Medication Frequencies and FHIR Timing Data Type
Event-Based Timing /effectiveTime[operator=”A” and xsi:type=”EIVL_TS”] …/event/@code …/offset	.dosageInstruction.timing.repeat.when .dosageInstruction.timing.repeat.offset	@code vocabulary matches .when CDA offset must be converted to minutes for FHIR
/routeCode	.dosageInstruction.route	CDA coding ↔ FHIR CodeableConcept
/doseQuantity	.dosageInstruction.doseAndRate.doseQuantity	CDA ↔ FHIR Quantity
/rateQuantity	.dosageInstruction.doseAndRate.rateQuantity	CDA ↔ FHIR Quantity
/consumable/manufacturedProduct/manufacturedMaterial/code	.medicationCodeableConcept	CDA coding ↔ FHIR CodeableConcept
/author	.requester & Provenance	CDA ↔ FHIR Provenance
/author/time	.authoredOn	Earliest, if more than one. CDA ↔ FHIR Time/Dates
/precondition	.asNeededBoolean = true	The presence of a precondition element indicates asNeededBoolean should be true. More complex maps may be possible with .asNeededCodeableConcept.
Indication /entryRelationship[@typeCode=”RSON”]/observation/value	.reasonCode	CDA coding ↔ FHIR CodeableConcept
Free text sig /entryRelationship/substanceAdministration[code/@code=”76662-6”]/text	.dosageInstruction.text
Instruction Activity /entryRelationship[@typeCode=”SUBJ” and @inversionInd=”true”]/act	.dosageInstruction.patientInstruction .dosageInstruction.additionalInstruction	act/text or act/code/originalText can map to patientInstructions. If coded, can map to additionalInstruction.
Comment Activity /entryRelationship/act[code/@code=”48767-8”]/text	Annotation .note

1. XPath abbrievated for C-CDA Medication Activity as:
ClinicalDocument/component/structuredBody/component/section[code/@code=”10160-0”]/entry/substanceAdministration

Illustrative example

Click on Here To See Highlighted Example

Links to example content

The consensus mapping example developed through multiple vendors are available below:

• Medication CDA example
• MedicationRequest FHIR example

Prior work and Expanded Spreadsheets

As reviewed in the methodology, a more comprehensive review was performed via spreadsheets. These spreadsheets have been consolidated and further revised in the tables above but are provided for reference here