As a follow-up to last month’s post, one of the more interesting outcomes of the ONC-led health IT initiatives is not just the coalescence around HL7 standards, but the central role the HL7 Clinical Document Architecture (CDA) has been accorded among interoperability strategy.
While there are necessary supporting standards for transport, security, vocabulary and infrastructure, none emerge as essential to interoperability. There are always alternatives, even to the highly favored DIRECT project transport.
- Messages, for ordering and receiving medications, labs and imaging, remain necessary but with increasingly niche focus.
- The concept of orders and as documents has arisen, in fact, as the Standards and Interoperability (S&I) Framework wrestles with coordinated care plans.
The CDA and XML arose together from roots in SGML, first in the Kona project 15 years ago, which established the base architecture, and then, in fusion with HL7. Key principles from that period remain leading experts of the CDA both within and without the HL7 Structured Documents Work Group. Adhering to its foundational tenets – that a document must be human readable, persistent and authored – the CDA has emerged as the contextual container of choice for sharing a range of clinical, administrative and financial information.
The CDA has been adopted both under the prior administration’s HITSP method and the current administration’s HITECH process for use as a clinical summary. In turn, the clinical summary, usually understood as the Continuity of Care Document (CCD) implementation guide for CDA, has become the Swiss Army Knife of implementation guides.
Its flexibility and adaptability led to a profusion of “summaries” whose optionality became increasingly difficult for different EHR systems to process. In Meaningful Use Stage 1, the HITSP C32 was chosen to constrain the CCD/CDA without understanding that C32 itself required context and constraints for specific use cases as provided in HITSP Interoperability Specifications.
In the absence of such Interoperability Specifications, HL7 and the ONC’s S&I Framework collaborated on the Consolidated CDA (C-CDA). The C-CDA is an implementation guide for nine specific CDA document types including a clinical summary, progress note, discharge summary and others.
This guide imposed constraints on the specific documents.
- It made data entries and their sections mandatory or conditionally optional, in a sense, making the documents “self-contained” without need of another guide.
- While this eased the receiver’s processing challenges and expected information content, it made the document types rigid without a clear method for formal extensions or adaptions.
Under the proposed rules for Meaningful Use Stage 2, the C-CDA based documents would be used as clinical summaries in all transitions between providers and as the basis for exchanges with and for patients. An almost immediate finding was that the C-CDA document types did not fully align with either the CMS or ONC rules.
There is now a current effort within the S&I Framework to create companion guides to show implementors how to both meet the requirements of Meaningful Use, Stage 2, as well as the clinical best practices developed as part of the Transitions of Care initiative. Once again, we are layering multiple constraint sources upon a CDA implementation.
But beyond transitions of care, the CDA is used in the S&I/CMS collaboration for electronic submission of medical documents and other initiatives including data segmentation for privacy, longitudinal care coordination and query health. While this focus well demonstrates the consensus commitment to selecting a single standard wherever possible, it also shows the challenges of making one standard meet many, diverse requirements.
We should expect ongoing tension between optionality and conformance, between flexibility and predictability. More than that, we will see the challenge of making the CDA more than a document; but instead, the CDA becomes a message, possesses internal logic, balances atomic level data with unifying context and gracefully handling multiple digital signings.
