C-CDA on FHIR, published by HL7 International / Cross-Group Projects. This guide is not an authorized publication; it is the continuous build for version 2.0.0-ballot built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/ccda-on-fhir/ and changes regularly. 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 Status

C-CDA may list a medication state (statusCode) 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. C-CDA also provides ambiguous guidance with respect to mood: completed and planned cases are well-defined, but active or ongoing cases are not addressed. We provide maps for both status and mood elements, but care is necessary to ensure C-CDA authors' intentions are understood.

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 (MedicationRequest)

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

C-CDA to FHIR (Medication)

MedicationRequest (and other resources) may represent the medication as a simple CodeableConcept. But when additional information about the medication needs to be conveyed, a Medication resource should be created instead and referenced by the MedicationRequest resource. Implementers may also opt to always create Medication resources.

Example

Links to example content

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

• Medication CDA example
• MedicationRequest FHIR example