Consolidated Clinical Document Architecture (C-CDA)

Key facts

Developed by

HL7 International, with the ONC Standards and Interoperability Framework

Built on

HL7 Clinical Document Architecture Release 2 (CDA R2)

Format

XML documents with a header and coded, templated sections

Common certification version

C-CDA Release 2.1

What is C-CDA?

A clinical document is a complete, attested record of care, such as a discharge summary or referral note, meant to be read by people and processed by software. The HL7 Clinical Document Architecture (CDA) defines an XML format for such documents, and C-CDA is the U.S. implementation guide that specifies how common document types should be built.

The word Consolidated refers to its origin: HL7 and the ONC Standards and Interoperability Framework merged several overlapping earlier specifications, including the HITSP C32 and the Continuity of Care Document, into one library of templates. Federal health IT certification has required C-CDA for years, which made it the standard format for summary of care records exchanged between electronic health records (EHRs).

How a C-CDA document is structured

Every C-CDA document combines a header with a body of sections:

Document types include the Continuity of Care Document (CCD), Discharge Summary, Referral Note, Consultation Note, History and Physical, Progress Note, Procedure Note, Operative Note, Care Plan and Transfer Summary.

• Header: metadata about the patient, authors, organizations, encounter and document type.
• Sections: such as Allergies, Medications, Problems, Results, Procedures, Immunizations and Plan of Treatment, each identified by a LOINC code.
• Entries: machine-readable data inside sections, coded with vocabularies such as SNOMED CT, RxNorm and LOINC.
• Narrative text: a human-readable block in each section that carries its attested clinical content.

Why C-CDA matters

C-CDA documents are how most outside records arrive in a U.S. EHR:

• Transitions of care: certified EHRs create and receive C-CDA documents when patients are referred or discharged, often over Direct secure messaging.
• Nationwide exchange networks that let providers query for outside records commonly return C-CDA documents, typically CCDs.
• Patients who download their record from a patient portal often receive a C-CDA file.
• Parsing C-CDA is a common way to extract structured problems, medications and results from outside records, though quality and completeness vary by sending system.

C-CDA vs FHIR

C-CDA and FHIR are both HL7 standards and often carry the same data, described by USCDI. C-CDA packages information into whole documents, while FHIR exposes individual resources through APIs that can be queried as needed. Newer federal rules emphasize FHIR APIs, but C-CDA remains in wide use for document exchange, and the two are expected to coexist.