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 ENV13606 - Prestandard for EHCR Communication Part 4 - Messages for exchange of information

XML-EDI Project - using XML for EDI EU Information Society Initiative for Standardisation

(ISIS)

XMLEPR Project - validation of the message 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 Propose good practice guidelines for XML/EDI Identify benefits & issues raised by XML/EDI

Validation of a draft of ENV13606 Confirm it meets UK NHS needs for GP to GP

transfer of patient records Propose revisions where needed to meet needs Identify needs for implementation guidelines

Background to healthcare record messages in the XML/EDI project

Background EHCR Communication Prestandards

Part 1 - Extended Architecture A Standardised view of EHCR information

Part 2 -Term List High-level categories & annotations

Part 3 - Distribution Rules A Standard way to express access rules

Part 4 - Messages Standard messages for EHCR

communication

ImplementableMessage

Specification

Syntax

ScopeSpecification

Userrequirements

Scenarios

GeneralMessage Description

HierarchicalGMD

Domain InformationModel

CEN TC251 Message Development Method

Communicationroles & services

Content Dependent

Proposed EHCRmessage data items

plain textplain text

quantifiable observationquantifiable observation

medicationmedication

structured codedstructured coded

record component

record component

eventevent

physical entity referencephysical entity reference

external data referenceexternal data reference

patient related partypatient related party

community definedcommunity defined

data itemdata item

person identifierperson identifier

person nameperson name

languagelanguage

addressaddress

telecomtelecom

related locationrelated location

a type of

EHCR message structure

specialised as1contains

1..*

specialised as

1..*

EHCR extractEHCR extract

original component

complex

original component

complex

record component

record component

link itemlink item

data itemdata item

folderfolder

compositioncomposition

headed section

headed section

1

EHCR messageEHCR

message

clustercluster

Coding, terminology & semanticsPresent healthcare data structures

Allow use of a variety of coding schemes ENV13606 Part 2 Term List provides a

minimum set of heading context terms

Improved communication requires Standard terms, qualifiers and classifications Mapping between terms and classifications

An interesting development Merger between the UK NHS Clinical Terms

(Read Codes) and SNOMED-RT

Is cheese extended chalk?

But HTML is a layout

mark-up format XML represents data

HTML uses fixed tags XML enables tags to be

purpose-defined

But Chalk is good for

display Cheese is nourishing

Chalk is hard Cheese soft or resilient

Both based on SGML Both contain tags

Both are edible solids Both contain calcium

BackgroundHTML & XML -- Chalk & Cheese Is XML extended HTML?

Mapping from UML models of messages to XML

Mapping message models for implementationMapping to EDIFACT

Difficult manual process Conformance to models unverifiable

Mapping to XML Automatable process Preserves structure of model Verifiable conformance Easier profiling Opportunity for ISO led convergence with HL7

Mapping - General Points

Message Development Methods lead to syntax independent models

Limits of automation Extra information needed in models to

support maps UML may not be rich enough!

Retain links back to the model

Mapping messages or models

XML to represent UML models generalised DTD possible content represents classes & relationships

XML to represent information storage Freer use of XML cross-references (e.g. ID &

IDREF)

Messaging environment some relationships by nested containment others refer to instance Ids not in message

Mapping classes

Concrete classes Mapped to XML-Elements

Abstract (generalised) classes Represented as XML-Entities Add to the content model

• In XML-Elements for classes specialised from them

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

Metadata such as:• Coding scheme identifier for a code value • The language of the content (xml:lang)

Status or typing data that affects processing Possibly for unique IDs ("ID" & "IDREF”) Enumerated data types (pragmatic reasons)

Mapping common classes

Common Class XML-Element Example:

• “PersonName" in "PatientMatchingInfo”

ORXML-Element specific to each attribute

with derived content Example:

• "AlternativeName" in "PatientMatchingInfo”

Mapping to DTDs or XML Schema

Mapping to DTDs now because they are: Stable Well supported by software

Schema proposals offer major advantages More flexible constraints Data Typing Archetypes 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 XMLEPRUK NHS GP computing

The situation 95% of UK GPs have computers 50% use these computers for clinical patient

records

GP computer systems in the UK Three major suppliers of GP systems Twelve widely used systems or versions Different record structures

None transfer records when patients move

Clinical validation

What is clinical validation of a message? Suppliers of diverse systems map real record

from their systems into the message structure Clinical professionals review original records and

the messages generated Look for inconsistencies, missing or added info. Determine whether the representations are

“safe”

XML used for validation because it offered Direct mapping from message models 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

ObserveCompare &Comment

Mapping

Experts

Clinicians

Comment and resolution

EHCR information

Specifications and rules

XMLEPR projectValidation of GP to GP communicationSupplier results

Four leading GP system suppliers populated the messages with information from their systems

Found XML learning-curve/implementation easier than EDIFACT

Viewers used for clinical validation IE5 XML-Notepad 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

Reported as formal comments to the Project Team responsible for the draft prestandard

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 Accepted by ballot on 29 June 1999 Comments from use will be monitored for the next

revision in 2-3 years time

ISIS XML/EDI project continues to end of year Further recommendations and demonstrations

expected

ISO TC215 Health Informatics May draft guidelines for use of XML in messaging

References

Material about the message and links to other sites

http://www.clinical-info.co.uk CEN TC251 Standards including ENV13606

http://www.centc251.org XMLEPR project

http://www.CommunicationsPlanning.co.uk/infopages Other XML/EDI information

http://www.tieke.fi/isis-xmledi

Healthcare uses of XML

Application

User Interface

ViewEnter

ReadWrite

Data storeED

I Inte

rface

Application

User Interface

View Enter

Read Write

Data storeED

I In

terf

ace

Messages in XML

Messages in XML

Application

User Interface

ViewEnter

ReadWrite

Data storeX

ML p

ublish

er

Application

User Interface

View Enter

Read Write

Data store

XM

L doc

um

ent

Browser

API

Data store

XML publisher

Application

User Interface

View Enter

Read Write

Data store

XML

docu

men

t

Browser

API

Data store

ExtractExtract

Extr

act

Browsable referencematerial on web sites

Application

User Interface

View Enter

Read Write

Data store

XML

docu

men

t

Browser

API

Application

User Interface

ViewEnter

ReadWrite

Data storeX

ML a

rch

i ver

Application

User Interface

View Enter

Read Write

Data store

XM

L

Browser

API

ArchiveXML

XM

L a

rch

ive re

ad

erXML

Application

User Interface

ViewEnter

ReadWrite

Application

User Interface

View Enter

Read Write

Data store

Browser

API

Data store as XML documents

XM

L doc

um

ent

Application

User Interface

ViewEnter

ReadWrite

Application

User Interface

View Enter

Read Write

Data store as XML documents

References

Material about the message and links to other sites

http://www.clinical-info.co.uk CEN TC251 Standards including ENV13606

http://www.centc251.org XMLEPR project

http://www.CommunicationsPlanning.co.uk/infopages Other XML/EDI information

http://www.tieke.fi/isis-xmledi