Model Formulation: HL7 Clinical Document Architecture, Release 2

j J Am Med Inform Assoc. 2006;13:30–39. DOI 10.1197/jamia.M1888. Clinical Document Architecture, Release One (CDA R1), became an American National Standards Institute (ANSI)– approved Health Level 7 (HL7) Standard in November 2000, representing the first specification derived from the HL7 Reference Information Model (RIM). CDA, Release Two (CDA R2), became an ANSI-approved HL7 standard in May 2005 and is the subject of this article, where the focus is primarily on how the standard has evolved since CDA R1, particularly in the area of semantic representation of clinical events. The basic model of CDA R2 is essentially unchanged from CDA R1. A CDA document has a header and a body. The header identifies and classifies the document and provides information on authentication, the encounter, the patient, and the involved providers. The body contains the clinical report, organized into sections whose narrative content can be encoded using standard vocabularies. The main evolutionary step in CDA R2 is that, whereas CDA R1 only used the RIM to derive the header, in CDA R2 both header and body are fully RIM derived. CDA R2 enables clinical content in the document body to be formally expressed to the extent that it is modeled in the RIM, coupled with terminology. CDA R1 is in use worldwide, and many of these sites are already making the transition to CDA R2. Both Finland and Greece expect to have the majority of their populations’ health records accessible in national information infrastructures within the next two or three years where they have been using CDA documents since the release of CDA R1. The cost-effective and rapid proliferation of accessibility to clinical information in these countries relies heavily on CDA documents created from Web-based, small office electronic health records and from legacy hospital information systems. Several sites have developed decision support applications using CDA R1 with local extensions or prenormative drafts Affiliations of the authors: Kaiser Permanente, Pasadena, CA (RHD, PVB); Alschuler Associates, LLC, East Thetford, VT (LA); Consultant, Laguna Beach, CA (SB); Mayo Clinic, Rochester, MN (CB); LAI Technology, Homewood, IL (FMB); Amnon Shabo (Shvo), IBM Haifa Research Lab, Haifa, Israel (AS). It is impossible to acknowledge all those whose foundational work has led to the development of the HL7 Development Framework and the HL7 Reference Information Model, from which CDA R2 derives. That CDA R2 is even possible is thanks to the years of work that have gone into the creation and consensus around these foundational components. The authors acknowledge and thank the HL7 organization and membership for providing challenging use cases, for striving toward greater and greater semantic interoperability, and for creating an atmosphere of camaraderie where people work together to solve real health care challenges that benefit from interoperability solutions. Correspondence and reprints: Robert H. Dolin, MD, 411 N. Lakeview Avenue, Anaheim, CA 92807; e-mail: . Received for review: 06/12/05; accepted for publication: 09/20/05. 30 DOLIN ET AL., HL7 CDA R2