Semantic Mapping and HL7

robert.worden@charteris.com

Why Mapping?

• HL7 have built UML semantic models of healthcare (RIM, RMIMs, CDA…)

• If everybody migrated to these models, many interoperability problems would be solved

• Suppliers cannot do this; they have big commitments to other models and structures

• They could map to the HL7 models; mapping is much easier than migrating

• So HL7 needs to publish shareable mappings to existing standards and data structures

Why Semantic Mapping? To Handle Structure Clashes

• Most mapping tools only map data values• These are the leaves of message trees• Structure clashes (e.g. multiplicity) arise on non-leaf

nodes, deep in the trees• Most mapping tools don’t address them• Therefore the translations don’t work• So people drop the tools and hand-code

Message AMessage B

mappings

Structure Clashes Arise from Associations

• ‘Deep’ message A represents the association X=>Y by nesting of elements• ‘Shallow’ message B represents the same association by shared key values• This causes a structure clash• You cannot translate from A to B without knowing how they each represent the

same association• Therefore semantic mapping is needed, to drive accurate translations

Message A Message B

Class X

Class Y

UML Class Model

object

association

property

association

Mappings in Progress

• Pharmacy V2-V3 (Pharmacy TC)

• Various V2-V3 (ItalTBS)

• HIPAA X12 to V3 (FM TC)

• CCR – CCD (various vendors)

• Relational database – V3 (basic demonstrator)

Example: CCR and CCD

• CCD and CCR are complex structures (typical nesting depth: 6 – 12)

• They have many structure clashes (CCR uses shared keys)

• They have both been mapped to a CCD semantic model (a few days’ work for CCR)

• The mappings give accurate translations and round trips – translating thousands of data items

• Mapping exposes the problems in CCR

Mappings for ARRA/HITECH

CCRV 2.5.1

ApplicationDatabase

ApplicationDatabase

ApplicationDatabase

NCPDP

HIPAAX12

ApplicationData Model

CDA +Templates

V3 RMIM

Benefits and Issues

• Mappings reveal the problems clearly and early

• Any-to-any translations can be generated from the mappings (=>rapid testing)

• By mapping an application data model to CDA, you will get translations to and from CDA, V2.5.1, CCR ….

• Managing templates is a big problem• Versions are a big problem

Semantic Mappings - Summary

• Declarative, simple where they can be simple, viewable (e.g. Excel)

• A specification for semantic interoperability• Auto-generate runnable transformations• N*(N-1) transformations from N sets of

mappings• Rapidly testable (=> test-driven

mapping)• Mapping exposes semantic problems

(gaps, ambiguities)