Development of a Visual Editor for the Definition of HL7 CDA Archetypes

David Moner, José Alberto Maldonado, Diego Boscá, Alejandro Mañas and Montserrat Robles

Grupo de Informática Biomédica, Instituto Universitario ITACA,Universitat Politècnica de València, Spain

damoca@upv.es

Introduction

HL7 and archetypes in the same sentence?The fight begins?

No!We are looking for

collaboration, rather than confrontation

2

Introduction

• Two main standards for EHR data representation in the arena:

HL7 CDA is a widely adoptedstandard for the representation ofclinical documents.

Templates are a mechanism todefine specific schemas ordocument profiles. It givesinstructions for the creation ofspecific CDA instances.

Templates, in the form ofimplementation guides, are notdirectly computable, but orientedto human interpretation.

ISO EN 13606 is a standard for thesemantic interoperability of EHRinformation.

Archetypes are a mechanism forthe definition of EHR datastructures and their meaning. Itgives instructions for the creationof specific ISO EN 13606 instances.

Archetypes are based on acomputable formal model that canbe also used with any otherstandard.

3

HL7 CDA ISO EN 13606

Introduction

• The use of archetypes together with HL7 CDA can resolve several weaknesses of the template approach:

– To provide a formal framework for the definition of clinical models.

– To improve the reuse and governance of those models by taking profit of the specialization and aggregation possibilities of archetypes.

– To facilitate the direct involvement of health professionals in the archetype definition process.

– To provide a more powerful and expressive definition of the semantics (terminology bindings) and data constraints that define the clinical information model.

4

The main objective of the work was to develop technology and tools to use the archetype methodology as an HL7 CDA

template definition format.

Methods

• A reference model provides the pieces and basic structure to represent any clinical data and its context information (dates, authorship, etc.).

5

• A dual model architecture separates the representation of data structures from their formal definitions.

ISO EN 13606HL7 CDA

openEHR

• An archetype represents the instructions about how to combine those pieces into a data structure schema that also has a clinical defined meaning (e.g. a discharge report or a medication instruction).

Methods

• LinkEHR Editor is a reference model-independent archetype editor developed by the IBIME group.

– It can be used for the definition of archetypes based on any reference model that has been previously imported into the tool.

– Additionally to this generic interface, specific and clinical-oriented interfaces can be developed to ease the use of the tool by archetype designers.

– It has been already used with ISO EN13606, openEHR, Hl7 CDA, CDISC ODM, ASTM CCR and MML (Japanese standard)

6

www.linkehr.com

Results

• HL7 reference model XML Schema was imported into LinkEHR

• Some problems faced:– XML-oriented vs. Object-oriented methodologies (mixed nodes and

choices of mandatory elements)

– Preservation of namespaces

7

Results

• A specific HL7 CDA interface was implemented– Hides the technical HL7 CDA structures and classes that do not add

clinical value to the user.

– There exists a visualization option to Access to the technical view at any time.

8

Results

• Forms have been created to simplify the definition od constraints on HL7 CDA attributes.– These forms are associated to each node of the archetype tree.

9

Results

• HL7 CDA internal terminologies and LOINC codes have been included into the tool to ease access to them.

10

Conclusions

Constrained nodeNumber of steps(generic editor)

Number of steps (simplified editor)

Section 16 4

CustodianOrganization 11 6

LabeledDrug 36 10

11

Interactions needed to create a node constraint

• A method for measuring the simplification of the modelling process is by analyzing the number of steps or interactions needed to define a constraint.

Conclusions

• LinkEHR Editor has been used to implement the HL7 CDA template of the Genetic Test Report (GTR) – a 107 pages document.– 4 CDA archetypes were implemented following the indications of the

GTR guide: Genetic report, Cytogenetics, Genetic variation and Test result information.

– Over 50 different data items (archetype nodes) were defined and constrained, adding the name of the node, its textual description, terminology binding, occurrences, templateId and data type selection.

12

Archetypes can represent faithfully all

constraints defined in a CDA template

David Moner CanoGrupo de Informática Biomédica (IBIME)

Instituto ITACA, Universitat Politècnica de Valencia, Spain

damoca@upv.eshttp://www.ibime.upv.es/

Thank you for your attention!

Questions?