1. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Observations on Clinical LOINC CG Chute 29 Sept 2003

2. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Reason for visit… l Chris likes LOINC l He whined about some structure issues l Stan said: “Whine not, tell us do.” l Here as a friend of LOINC

3. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Why does Chris care about LOINC Structure Usual reasons for wanting to use LOINC: l Cohort identification and retrieval l Decision support triggers l Outcome research, Quality improvement l Etc. l All require aggregation!

4. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Aggregation over LOINC Codes l Management of each axis/component u Collapse across axes combinations u Not always trivial – Sodium Component l Would be helped enormously with Axes ontologies u Underway for lab LOINC (Steindel, et al.)

5. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Granularity of LOINC codes l Well-grounded in lab LOINC “The level of detail in the LOINC definitions was intended to distinguish tests that are usually distinguished as separate test results within the master file of existing laboratory systems.” l Less obvious basis for Clinical LOINC u No Silver Book

6. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Information model vs. Terminology model l What role does a LOINC code play? u Fill in an HL7 message “slot” l What is the boundary between the message structure and the clinical LOINC structure? l Should the boundary rest on capacity for trivial aggregations? (gime all BPs)

7. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Structure in Clinical LOINC on the 6-part information model l Virtually all Clinical LOINC tests invoke the 6-part information model u 0.3% (21) have blank System component l Liberal but inconsistent use of “subclass” (period separator) and subtype names l The term “class” is inconsistent u LOINC class vs. analyte class

8. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Enumerations about Clinical LOINC Not homogeneous l 5851 Clinical entries in LOINC v2.09 l 5390 (92%) have PT as Time Aspect l Distribution of Scale: 47DOC 47DOC 27MULTI 27MULTI 1555NAR 1000NOM 172 ORD 172 ORD 6 ORDQN 6 ORDQN 3037 QN 6 SET 6 SET

9. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Should the 6-part model dominate in clinical LOINC? l Some concepts are very simple u Body mass, NOS; Height… u Perhaps most are complex, with more than 6 components l Bearing aggregation logics in mind, should all period/carrot (./^) delimiters be strippable?

10. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Compound Expressions Among 5851 Clinical entries Period. ^+/nullComponent188374254266- Time-119--- System20731071167421 Method1377-18--

11. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Frequency of Compound Expressions Within Component OccurrenceFrequency Periods (.) ^+/ 11490 726 72652241 2 271 271 16 16 2 23 23 3 18 18 2 4 26 26 5 3 6 4 7 1 Total188374254266

12. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Frequency of Compound Expressions Within Component Occurren ce FrequencyAny Periods (.) ^+/ 113901490 726 72652241 2 691 691 271 271 16 16 2 23 23 3 101 101 18 18 2 4 13 13 26 26 5 3 6 8 4 7 2 1 8 3 TotalTotal188374254266

13. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Some Components with two ^ separators l DIFFUSION CAPACITY.CARBON MONOXIDE^^ADJUSTED FOR HEMOGLOBIN l DIFFUSION CAPACITY^^ADJUSTED TO BODY CONDITIONS l TIDAL VOLUME.EXPIRED.SPONTANEOUS^^UNCORRECTED FOR COMPRESSIBLE GAS VOLUME.SETTING l TIDAL VOLUME.EXPIRED.SPONTANEOUS^ON VENTILATOR^CORRECTED FOR COMPRESSIBLE GAS VOLUME l TIDAL VOLUME.SPONTANEOUS+MECHANICAL^ON VENTILATOR^CORRECTED FOR COMPRESSIBLE GAS VOLUME l TIDAL VOLUME.SPONTANEOUS+MECHANICAL^ON VENTILATOR^CORRECTED FOR COMPRESSIBLE GAS VOLUME/BODY WEIGHT l TIDAL VOLUME.SPONTANEOUS+MECHANICAL^ON VENTILATOR^UNCORRECTED FOR COMPRESSIBLE GAS VOLUME l VOLUME^AT 1.0 S POST FORCED EXPIRATION^POST BRONCHODILATION l VOLUME^AT 1.0 S POST FORCED EXPIRATION^PRE BRONCHODILATION l VIEWS^W CONTRAST.XXX TRANSHEPATIC^W HEMODYNAMICS

14. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Some Components with five. Separators and one with six l CAPACITY.VITAL.FORCED.POST BRONCHODILATION/CAPACITY.VITAL.FORCED PREDICTED l VOLUME.AT 25-75% OF FORCED EXPIRATION.MEASURED.POST BRONCHODILATION/VOLUME.AT 25-75% OF FORCED EXPIRATION.PREDICTED l VOLUME.AT 25-75% OF FORCED EXPIRATION.MEASURED.PRE BRONCHODILATION/VOLUME.AT 25-75% OF FORCED EXPIRATION.PREDICTED l BLOOD FLOW.MAX.STENOSIS.INTERNAL CAROTID ARTERY/BLOOD FLOW.MAX.UNOBSTRUCTED.COMMON CAROTID ARTERY

15. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Hasty generalizations l The sub-syntax of clinical LOINC name components is complex (.^+/) l Composition syntax is wildly inconsistent l Parsing these puppies may mandate a call to the SPCA – not pretty

16. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. On ontologies l There do not appear to be consistent sets of terms from which clinical LOINC names are composed u Anatomy, timing, setting, adjustments l There do not appear to be consistent sub- axes within complex component names

17. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. So, What does Chris want done about it? Not a simple or easy problem l We must solve information/terminology model boundary problem l Exemplar issue of sub-message boundary u Template u Archetype u CEM (Clinical Expression Module)

18. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Once the miracle occurs (model boundaries agreed upon) Clinical LOINC would be well advised to l Recognize it is not analogous to lab test name structures (no Silver book master) l Have a terminology RIM l Entertain DMIMs u Where truncation of element implies aggregation l Define terminology tables to populate slots u Hierarchies which support aggregation

19. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. On syntax l The 6-part model may not be optimal for such complex expressions l DMIMs imply variable size and shape of components l Use of delimiters (.^+/) should be rigorously consistent or abandoned u And/or must always aggregate by truncation l Perhaps will require XML or OWL structures

20. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Historical analog l HL7 V2 was simple, spare, and usable l V2 did not scale well to complexity of clinical enterprise l Consistent and comparable messages are not dependable among V2 implementations l V3 imposes more rigorous formalisms to achieve comparable and consistent information interchange

21. © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission. Clinical LOINC (and other variants) l It may be time to consider “V3” style re- casting of the venerable LOINC structure l A formal, subset-able, terminology model may be desirable l One may chose to invoke Description Logic formalisms within element hierarchies l Syntax should evolve to correspond