XML used for Healthcare Messaging and Electronic Health Record Communication David Markwell - Clinical Information Consultancy Andrew Hinchley - Communication Planning Ltd

Three intertwined projects §CEN TC251 Healthcare Informatics Standards l ENV Prestandard for EHCR Communication l Part 4 - Messages for exchange of information §XML-EDI Project - using XML for EDI l EU Information Society Initiative for Standardisation (ISIS) §XMLEPR Project - validation of the message l UK National Health Service and Royal College of General Practitioners

Three parallel objectives §A standard message for health record transfer §Investigate XML as a syntax for EDI l Propose good practice guidelines for XML/EDI l Identify benefits & issues raised by XML/EDI §Validation of a draft of ENV13606 l Confirm it meets UK NHS needs for GP to GP transfer of patient records l Propose revisions where needed to meet needs l Identify needs for implementation guidelines

Background to healthcare record messages in the XML/EDI project

Background EHCR Communication Prestandards §Part 1 - Extended Architecture l A Standardised view of EHCR information §Part 2 -Term List l High-level categories & annotations §Part 3 - Distribution Rules l A Standard way to express access rules §Part 4 - Messages l Standard messages for EHCR communication

Implementable Message Specification Syntax Scope Specification User requirements Scenarios General Message Description Hierarchical GMD Domain Information Model CEN TC251 Message Development Method Communication roles & services Content Dependent

Proposed EHCR message data items plain text quantifiable observation medication structured coded record component event physical entity reference external data reference patient related party community defined data item person identifier person name language address telecom related location a type of

EHCR message structure specialised as 1 contains 1..* specialised as 1..* EHCR extract original component complex record component link item data item folder composition headed section 1 EHCR message cluster

Coding, terminology & semantics §Present healthcare data structures l Allow use of a variety of coding schemes l ENV13606 Part 2 Term List provides a minimum set of heading context terms §Improved communication requires l Standard terms, qualifiers and classifications l Mapping between terms and classifications §An interesting development l Merger between the UK NHS Clinical Terms ( Read Codes ) and SNOMED-RT

§Is cheese extended chalk? §But l HTML is a layout mark-up format l XML represents data l HTML uses fixed tags l XML enables tags to be purpose-defined §But l Chalk is good for display l Cheese is nourishing l Chalk is hard l Cheese soft or resilient l Both based on SGML l Both contain tags l Both are edible solids l Both contain calcium Background HTML & XML -- Chalk & Cheese §Is XML extended HTML?

Mapping from UML models of messages to XML

Mapping message models for implementation §Mapping to EDIFACT l Difficult manual process l Conformance to models unverifiable §Mapping to XML l Automatable process l Preserves structure of model l Verifiable conformance l Easier profiling l Opportunity for ISO led convergence with HL7

Mapping - General Points §Message Development Methods lead to syntax independent models §Limits of automation l Extra information needed in models to support maps l UML may not be rich enough! §Retain links back to the model

Mapping messages or models §XML to represent UML models l generalised DTD possible l content represents classes & relationships §XML to represent information storage l Freer use of XML cross-references (e.g. ID & IDREF) §Messaging environment l some relationships by nested containment l others refer to instance Ids not in message

Mapping classes §Concrete classes l Mapped to XML-Elements §Abstract (generalised) classes l Represented as XML-Entities l Add to the content model In XML-Elements for classes specialised from them l Create a choice structure for specialisations In XML-Elements that include the generalisation

Mapping attributes §Most attributes mapped to an appropriate XML-Element §Attributes mapped to XML-Attributes include l Metadata such as: Coding scheme identifier for a code value The language of the content (xml:lang) l Status or typing data that affects processing l Possibly for unique IDs ("ID" & "IDREF”) l Enumerated data types (pragmatic reasons)

Mapping common classes §Common Class XML-Element l Example: “PersonName" in "PatientMatchingInfo” OR §XML-Element specific to each attribute with derived content l Example: "AlternativeName" in "PatientMatchingInfo”

Mapping to DTDs or XML Schema §Mapping to DTDs now because they are: l Stable l Well supported by software §Schema proposals offer major advantages l More flexible constraints l Data Typing l Archetypes l Extensibility §Mapping to Schemas next logical step

XML/EDI in use to validate the healthcare record message for UK GP to GP communication

Background to XMLEPR UK NHS GP computing §The situation l 95% of UK GPs have computers l 50% use these computers for clinical patient records §GP computer systems in the UK l Three major suppliers of GP systems l Twelve widely used systems or versions l Different record structures §None transfer records when patients move

Clinical validation §What is clinical validation of a message? l Suppliers of diverse systems map real record from their systems into the message structure l Clinical professionals review original records and the messages generated l Look for inconsistencies, missing or added info. l Determine whether the representations are “safe” §XML used for validation because it offered l Direct mapping from message models l Freely available viewers and software libraries

The validation process Viewer Instance of XML message/document PT29 Provide EHCR Message Provide EHCR DTD GP system Export Layout Observe Compare & Comment Mapping Experts Clinicians Comment and resolution EHCR information Specifications and rules

XMLEPR project Validation of GP to GP communication §Supplier results l Four leading GP system suppliers populated the messages with information from their systems l Found XML learning-curve/implementation easier than EDIFACT §Viewers used for clinical validation l IE5 l XML-Notepad l Specialised viewer developed in the project

Results of validation §The Provide EHCR message is substantially able to convey the information present in a majority of existing GP Electronic Patient Records (in the UK) §Some weaknesses in the draft message proposal l Reported as formal comments to the Project Team responsible for the draft prestandard l All these comments were accepted and resulted either in changes to the message or clarifications in the documentation §Further validation, piloting and implementation recommended to the UK NHS

Other results and progress §EHCR Communication Prestandards l Accepted by ballot on 29 June 1999 l Comments from use will be monitored for the next revision in 2-3 years time §ISIS XML/EDI project continues to end of year l Further recommendations and demonstrations expected §ISO TC215 Health Informatics l May draft guidelines for use of XML in messaging

References §Material about the message and links to other sites l §CEN TC251 Standards including ENV13606 l §XMLEPR project l §Other XML/EDI information l

Healthcare uses of XML

Application User Interface View Enter Read Write Data store EDI Interface Application User Interface View Enter Read Write Data store EDI Interface Messages in XML

Application User Interface View Enter Read Write Data store XML publisher Application User Interface View Enter Read Write Data store XML document Browser API

Data store XML publisher Application User Interface View Enter Read Write Data store XML document Browser API Data store Extract

Browsable reference material on web sites Application User Interface View Enter Read Write Data store XML document Browser API

Application User Interface View Enter Read Write Data store XML archiver Application User Interface View Enter Read Write Data store XML Browser API Archive XML XML archive reader XML

Application User Interface View Enter Read Write Application User Interface View Enter Read Write Data store Browser API Data store as XML documents XML document

Application User Interface View Enter Read Write Application User Interface View Enter Read Write Data store as XML documents

References §Material about the message and links to other sites l §CEN TC251 Standards including ENV13606 l §XMLEPR project l §Other XML/EDI information l