Archetypes in HL7 2.x Snomed-CT “Computable Medical Records” Andrew McIntyre Medical-Objects NEHTA Snomed-CT Workshop
Terminology is for Computers Humans understand text pretty well Computers are pretty hopeless at it –Much better with codes –Can manage much more in memory –Are obsessive and tireless –A path to decision support –Snomed-CT is for computers
Focus Concept
Attributes = Post Co-Ordination Attributes are defined by model –Vary depending on type of statement –Qualify concepts
Context of Statements Past History Family History Planned Possible etc Every statement needs context –Default context Known present About patient Current or specified
Context added to statements Removes much ambiguity
Context Example Procedure Context These are “Values”
Snomed –CT Abstract logical Model under development –Conflicts/overlaps with some HL7 V3 structures HL7 V2 has administrative models –Limited clinical model (Medication mainly) It is possible to represent Snomed-CT Abstract Logical Model in HL7 V2 Requires tree structures within groups of OBX segments – Archetyped HL7 V2
Snomed Model Nested Name=Value pairs
In HL7 V2.3.1 OBX segments are designed to carry NAME=VALUE pairs with date Dotted Sub-ID for structure Relatively simple display rules –linear display is possible
Archetypes in V2 Very Compact representation OBX Sub-ID used for structure Only value nodes need to be included Works with existing display logic Requires CE support! Full semantic transfer SNOMED-CT Abstract model transmitted Requires knowledge of archetype
Multiple Inheritance Model Eg Cholecystectomy
Multiple Inheritance
Gello Statement
Requires Patient Model
Expressing Snomed-CT Model Snomed Grammar Fully supported by GELLO
Gello Can Exploit This
Gello can validate Need to ensure statements are valid wrt Model
GELLO equivalence
Snomed Constraints Archetype base Constraints restricts user to correct terms
Constraint Specification
MO Terminology Server Uses HL7 V2 or SOAP interface Lookup support with constraints Canonical form support Can run locally or remotely (transparent) SOA architecture GELLO integration Caches frequently used queries locally Available now via Communications clients
Summary Snomed-CT allows high level computability Must follow Snomed-CT Model Needs more structure –Archetypes in HL7 V2 can do this –Archetypes can constraint choices Gello, vEMR and Terminology Server allow computable medical Records Standards urgently needed for interoperability of records
Resources GELLO and GLIF demo available