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CDA USE IN THE PCEHR: LESSONS LEARNED One of the key foundations of the PCEHR is that the Clinical Document Architecture (CDA), an XML-based mark-up standard developed as part of HL7 v3, is used for all the clinical documents used in the PCEHR. This article does not purport to evaluate the PCEHR program itself, nor even how the PCEHR program used CDA, but to simply describe the lessons learned from using CDA for the PCEHR.
GRAHAME GRIEVE FACHI Consultant, Health Intersections grahame@healthintersections.com.au
Why did the PCEHR program use CDA? In May 2007, NEHTA published a document called Standards for E-Health Interoperability: An E-Health Transition Strategy. The purpose of this document was to recommend a standards approach for a broad range of eHealth information interchange requirements, with a particular focus on a national approach to shared electronic health records. This document rated the advantages and disadvantages of the following four approaches: extending existing use of HL7 v2 as far as possible; a document/ services-centric HL7 v3, based on CDA plus services defined by HL7 (HSSP); CEN 13606; and openEHR. It was a summary of a much larger document that assigned scores for each of these based on a series of criteria. The second option – CDA plus web services – got the highest score (although all the scores were close), and was therefore selected as the preference.
About the author Grahame Grieve is an internationally recognised expert in healthcare standards and interoperability. He consults to NEHTA, HL7 and the ISO, and is the CDA expert for the PCEHR. In 2011, he developed the Fast Healthcare Interoperability Resources (FHIR) framework, now a draft standard.
When the PCEHR project was initiated, this preference became the basis for the general architecture. The HSSP part was replaced by IHE XDS because by then, IHE had published XDS.b, which was based on a web services architecture. CDA was a late comer to the NEHTA work program. For several years prior to the
adoption of the CDA strategy, NEHTA had been working with stakeholders, including jurisdictions, professional colleges, and vendors, to describe a set of information exchanges (information models, and the services that supported them) that had been identified as providing the key opportunities for improving healthcare through better exchange. These identified packages had their own rich consultation and analysis history, and an existing methodology was used for describing and publishing these analyses. Today, these are published by NEHTA as the Core Information Components and the Structured Content Specifications. These specifications describe the logical contents of the document in a form that is independent of CDA, and therefore reusable in other formats and contexts. Within the PCEHR program, then, CDA is seen as a technical vehicle for exchanging/ persisting a logical package of data that conforms to pre-existing stakeholder agreements.
Lessons learned Now that the first round of the PCEHR implementation is nearly complete, there are a few lessons that we can learn about CDA.
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