Clinical Document Architecture

The Clinical Document Architecture (CDA ) is an HL7 erarbeiteter, XML-based standard for the exchange and storage of clinical content. Here, a CDA document a clinical document (eg, doctor's letter, Report of findings). There is no collection of several documents, such as in a patient record.


CDA Release 1 ( November 2000) and CDA Release 2 ( May 2005) have been accredited by the American National Standards Authority ANSI / ASTM. The CDA is considered the first official level of care based on XML.

CDA is part of the HL7 Version 3 standards. As with other parts of the HL7 Version 3 CDA standards based on the HL7 Development Framework ( HDF) has been developed and is based on the HL7 Reference Information Model (RIM ) and the HL7 version 3 data types.

Features and Construction

CDA documents provide the possibility of a standardized structured transmission of medical content. CDA documents are persistent.

A CDA document consists basically of two parts:

  • CDA header with information about the document and the event documented as well as the patient, the involved health care professionals etc.
  • CDA Body with the actual content such as clinical questions, observations, diagnoses, medication, treatment, information on re- presentation, suggested dates etc. The documentation can be divided into sections ( sections ). There are text formatting features such as lists and tables.

The focus is always on the communication between people ( human- to-human interoperability), ie, the documentation is always in text form. In addition, the readable text can be supplemented with information blocks, which can be used by the computer application (application interoperability).

The specification differentiates between three inter- stages (levels), which differ by the degree of structuring of the document content:

  • CDA Level 1: Representation of existing clinical documents in XML, focus on layout and basic formatting of text entries ( sections, highlighting, tables). Allows only limited interoperability, because the contents are not machine-readable. This means that documents can indeed neatly displayed from various systems, but not processed by machine. For example, contained in a CDA Level 1 document individual lab values ​​can not be automatically entered in a central laboratory values ​​table.
  • CDA Level 2: In addition to Level 1 value is placed on interoperability, while maintaining the free-text content of Level 1 was obtained. Level 2 adds a uniform structured description and outline of the contents (type of document, sections, subsections ). The individual components are standardized codes and code systems classified ( LOINC, SNOMED ).
  • CDA Level 3: Added to machine-readable data, so eg transferred laboratory values ​​can be automatically entered into the laboratory table of values ​​of the receiver. The structures used in this case are based on the HL7 RIM, so use the same data types and structures such as other HL7 -based communication processes, eg for the transmission of laboratory results.

But applies to all three levels of the primacy of the information contained in free text ( narrative block), the machine-readable data structures and always serve as a complement and can facilitate and support the processing of the information.