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HL7 TermInfo A standard for using SNOMED CT with HL7. David Markwell Principal Consultant - The Clinical Information Consultancy Ltd Chair of SNOMED International Concept Model Working Group Co-Editor – HL7 TermInfo Guide to use of SNOMED CT. Overview. What is TermInfo? - PowerPoint PPT Presentation
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Presentation copyright - The Clinical Information Consultancy (www.clininfo.co.uk)SNOMED Clinical Terms is a copyright work of the College of American Pathologists (www.snomed.org)
HL7 TermInfoA standard for using SNOMED CT with HL7
David MarkwellPrincipal Consultant - The Clinical Information Consultancy Ltd
Chair of SNOMED International Concept Model Working Group
Co-Editor – HL7 TermInfo Guide to use of SNOMED CT
2
Overview
What is TermInfo? Where did TermInfo come from? Why does TermInfo matter? What does TermInfo say? Where is TermInfo going?
3
What is TermInfo?
TermInfo is an HL7 Project developing standard guidance on use of Terminologies within Information models
The Information model focus is on HL7 Version 3 models including:
• HL7 Reference Information Model (RIM); and• Constrained Information Models (e.g. DIMs, RMIMs etc.)
• Particularly the Clinical Statement pattern
TermInfo Work Package 2 is the most active part of the project The Terminology focus of WP2 is SNOMED CT
4
A project launched by NASA in July 2004 To enable effective coding and structuring of
astronaut health records To decide how to use SNOMED CT in
information models derived from the HL7 Reference Information Model
Where did TermInfo come from?
Clinical semantics, the final frontier.
These are the voyages of the HL7 project TermInfo.
Its five-year mission: To explore strange old words.
To impart meaning to structured information.
To boldly code where no code
has gone before.
6
HL7 TermInfo coming down to earth
TermInfo was adopted by the HL7 Vocabulary TC in September 2004
Supported by the SNOMED International Standards Board since October 2004
7
Why does TermInfo matter?
The HL7 RIM is an information model It provides a structure that can be populated with
instances of information represented using a coded vocabulary
SNOMED CT is a reference terminology Terminology provides a coded vocabulary to
populate an information model with processable concepts
The objective of both HL7 and SNOMED is semantic interoperability Meaning depends on how the vocabulary and
structure fit together
8
Roger Tranquility,
we copy you
on the ground.
You got a bunch of guys
about to turn blue here.
We're breathing again.
Thanks a lot.
Meaning depends on the context of words within a sentence
9
Meaning depends on structure & vocabularyNotes on an English lesson
Jack where Jill had had had had had had had had had had been the correct answer Ten consecutive uses of the word “had” seems like nonsense Surprisingly punctuation can make it meaningful Question: Who was correct, Jack or Jill?
Jack, where Jill had had “had”, had had “had had”; “had had” had been the correct answer. Jack was correct!
Jack, where Jill had had “had had”, had had “had”; “had had” had been the correct answer. Jill was correct!
Meaning depends on structure
10
Meaning depends on structure & vocabularyMore notes on an English lesson
Even with the correct structure this is far from clear Jack, where Jill had had “had had”, had had “had”;
“had had” had been the correct answer. More specific vocabulary makes the meaning clearer
Jack where Jill had written “had had”, had written “had”, “had had” had been the correct answer.
Changing the structure makes the meaning unambiguous Where Jack had written “had”, Jill had written “had
had”. The correct answer had been “had had”. Meaning depends on structure and vocabulary
11
Structure and vocabularyA clinical example
Consider the meaning of the following similar looking sentences The result suggests exclusion of thyrotoxicosis The result suggests that thyrotoxicosis can be excluded The result suggests that thyrotoxicosis should be excluded The result suggests that thyrotoxicosis needs to be excluded
Can you be sure what each sentence is intended to mean?
12
Structure and vocabularyAn unconstrained HL7v3 / SNOMED CT example
Asthma Subject Family member
Family History of Asthma Subject Record target
ComponentFamily History Asthma
ComponentFamily History Family History of Asthma
ComponentFamily History Asthma value=true
ComponentHistory
Asthma
Subject Family member
Family History value=Asthma
Family History of Asthma
Family History of Asthma Subject Family member
13
Structure and vocabularyAn unconstrained HL7v3 / SNOMED CT example
Asthma Subject Family member
ComponentFamily History Asthma
ComponentFamily History Family History of Asthma
ComponentFamily History Asthma value=true
ComponentFamily History No Family History of Asthma
ComponentFamily History Asthma value=false
ComponentFamily History Asthma negationInd=true
Component negationInd=trueFamily History Asthma
No Family History of Asthma
Family History of Asthma
Family History of Asthma Subject Family member
Presentation copyright - The Clinical Information Consultancy (www.clininfo.co.uk)SNOMED Clinical Terms is a copyright work of the College of American Pathologists (www.snomed.org)
What does TermInfo say?
Some examples of the recommendations from the initial ballot draft
… plus a few updates …
15
Family history recommendation
Use SNOMED CT expression to explicitly represent a condition of a family member rather than relying on an HL7 “participation” association to convey this
Use the HL7 participation association if necessary to specify a particular person
Family History of Asthma SubjectFamily member
Family History of Asthma
16
General recommendation
Semantic interoperability requires a shared “Model of Meaning”
Information is often collected and stored based on a “Model of Use” This view needs to be transformed into a
normalized “Model of Meaning” for comparison A simplistic view of the “Model of Use” may prevent
reliable transformation to a common “Model of Meaning”
17
Recommendations on semantic overlaps (1)
Avoid use of optional HL7 attributes that restate meaning that can be clearly represented in a SNOMED CT expression
This applies to Act
• negationInd• certaintyCode
Observation and Procedure• methodCode• bodySiteCode
18
Recommendations on semantic overlaps (2)
Ensure consistency of mandatory HL7 attributes with any explicit context stated in a SNOMED CT expression This applies to
• HL7 moodCode and the ways it interacts with …• SNOMED CT “finding context” and “procedure context”
A table specifies which values of these are regarded as consistent with one another
19
Recommendations on semantic overlaps (3)
Apply any context implied by mandatory HL7 attributes to SNOMED CT expressions that do not include an explicit conflicting context For example, the HL7 moodCode “RQO” applied to
a procedure concept (without explicit context) replaces the default context “done” with “requested”
A table specifies the default finding and procedure contexts for each moodCode value
20
Recommendations on semantic overlaps (4)
Do not treat HL7 attributes and SNOMED CT concepts in a manner that creates new combinatorial contexts E.g. moodCode=“INT” (intent) with SNOMED CT
procedure context “requested” Does not mean• “intent to request …[procedure]”
• The “intent” applies to the procedure not the request.
It means• “requested …[procedure]”
• The “requested” merely refines the “intent”.
21
Recommendations of use HL7 Observation class to represent “nominalized statements” (1)
Nominalized statements are assertions about a clinical finding that cannot be consistently subdivided into a “code” for what was done; and a “value” for the result
Acceptable pattern Observation.code – an HL7 code meaning “Assertion” Observation.value – an expression that when normalized is
subsumed by one of the following• situation with explicit context (ConceptId 243796009)
• clinical finding (ConceptId 404684003)
Note: Change from current draft based on recent MnM ruling
22
Recommendations of use HL7 Observation class to represent “nominalized statements” (2)
Other representations of nominalized statements are deprecated but may be permitted for backward compatibility. These forms are only permitted where there is a reproducible
transformation that can be reliably applied to the convert them to the preferred acceptable pattern without loss of meaning
Example of a permitted deprecated pattern Observation.code – an expression that when normalized is
subsumed by one of the following• situation with explicit context (ConceptId 243796009) • clinical finding (ConceptId 404684003)
Observation.value (OMITTED)
Note: For backward compatibility this pattern regarded as equivalent to the acceptable pattern on the previous slide
24
Where is TermInfo going?
Ballot on Draft Standard for Trial Use (DSTU) in April 2006 Large number of comments reviewed and decisions
made on significant changes
Revision of the document now in progress Next ballot cycle - end 2006 / early 2007
25
Join the HL7 TermInfo Project at www.hl7.org
26
SNOMED CT – the future
Representatives of five Potential Charter Members (Australia, Denmark, Lithuania, New Zealand, and the United Kingdom) met with the College of American Pathologists (CAP) in Copenhagen to discuss the creation of a standards development organization to maintain and promote the SNOMED CT clinical terminology.
By the end of the two-day meeting, which took place from October 4th and 5th, all the Potential Charter members (including the Canada and the United States) and the CAP agreed in principle to move forward together toward their common goal of founding the SNOMED Standards Development Organization (SNOMED SDO).
www.snomed.org
With the emergence of the SNOMED SDO, TermInfo has become part of an international effort to assemble the pieces needed for clinical semantic interoperability
Observation
Procedure
Person
Role
Com
pone
nt
SupplyActRef
OrganizationDevice
Aut
hor
Subject
Is NASA interested in
TermInfo because of
the model in space ?