© copyright 2003, mayo foundation for medical education and research. all rights reserved, may not...

11LOINCLOINC © Copyright 2003, Mayo Foundation for Medical Education and Research. All rights reserved, may not be distributed without permission.

Observations on Clinical LOINCObservations on Clinical LOINC

CG ChuteCG Chute29 Sept 200329 Sept 2003


Reason for visit…Reason for visit… Chris likes LOINCChris likes LOINC He whined about some structure issuesHe whined about some structure issues Stan said: “Whine not, tell us do.”Stan said: “Whine not, tell us do.” Here as a friend of LOINCHere as a friend of LOINC


Why does Chris care aboutWhy does Chris care aboutLOINC StructureLOINC Structure

Usual reasons for wanting to use LOINC:Usual reasons for wanting to use LOINC: Cohort identification and retrievalCohort identification and retrieval Decision support triggersDecision support triggers Outcome research, Quality improvementOutcome research, Quality improvement Etc.Etc. All require aggregation!All require aggregation!


Aggregation over LOINC CodesAggregation over LOINC Codes Management of each axis/componentManagement of each axis/component

Collapse across axes combinationsCollapse across axes combinations Not always trivial – Sodium ComponentNot always trivial – Sodium Component

Would be helped enormously with Axes Would be helped enormously with Axes ontologiesontologies Underway for lab LOINC (Steindel, et al.) Underway for lab LOINC (Steindel, et al.)


Granularity of LOINC codesGranularity of LOINC codes Well-grounded in lab LOINCWell-grounded in lab LOINC““The level of detail in the LOINC definitions The level of detail in the LOINC definitions

was intended to distinguish tests that are was intended to distinguish tests that are usually distinguished as separate test results usually distinguished as separate test results within the master file of existing laboratory within the master file of existing laboratory systems.”systems.”

Less obvious basis for Clinical LOINCLess obvious basis for Clinical LOINC No Silver Book No Silver Book


Information model vs. Terminology modelInformation model vs. Terminology model What role does a LOINC code play?What role does a LOINC code play?

Fill in an HL7 message “slot”Fill in an HL7 message “slot” What is the boundary between the What is the boundary between the

message structure and the clinical LOINC message structure and the clinical LOINC structure?structure?

Should the boundary rest on capacity for Should the boundary rest on capacity for trivial aggregations? (gime all BPs)trivial aggregations? (gime all BPs)


Structure in Clinical LOINCStructure in Clinical LOINCon the 6-part information modelon the 6-part information model Virtually all Clinical LOINC tests invoke the Virtually all Clinical LOINC tests invoke the

6-part information model6-part information model 0.3% (21) have blank System component0.3% (21) have blank System component

Liberal but inconsistent use of “subclass” Liberal but inconsistent use of “subclass” (period separator) and subtype names(period separator) and subtype names

The term “class” is inconsistentThe term “class” is inconsistent LOINC class vs. analyte classLOINC class vs. analyte class


Enumerations about Clinical LOINCEnumerations about Clinical LOINCNot homogeneous Not homogeneous 5851 Clinical entries in LOINC v2.095851 Clinical entries in LOINC v2.09 5390 (92%) have PT as Time Aspect5390 (92%) have PT as Time Aspect Distribution of Scale:Distribution of Scale:

4747 DOCDOC 2727 MULTIMULTI

15551555 NARNAR10001000 NOMNOM

172 172 ORDORD 6 6 ORDQNORDQN

3037 3037 QNQN 6 6 SETSET


Should the 6-part model dominate in Should the 6-part model dominate in clinical LOINC?clinical LOINC? Some concepts are very simpleSome concepts are very simple

Body mass, NOS; Height…Body mass, NOS; Height… Perhaps most are complex, with more than 6 Perhaps most are complex, with more than 6

components components Bearing aggregation logics in mind, should Bearing aggregation logics in mind, should

all period/carrot (./^) delimiters be all period/carrot (./^) delimiters be strippable? strippable?


Compound ExpressionsCompound ExpressionsAmong 5851 Clinical entries Among 5851 Clinical entries

Period Period ..

^̂ ++ // nullnull

ComponentComponent 18831883 742742 5454 266266 --

TimeTime -- 119119 -- -- --

SystemSystem 20732073 10711071 167167 44 2121

MethodMethod 13771377 -- 1818 -- --


Frequency of Compound ExpressionsFrequency of Compound ExpressionsWithin ComponentWithin ComponentOccurrence Occurrence FrequencyFrequency

Periods (.)Periods (.) ^̂ ++ //11 14901490 726726 5252 24124122 271271 1616 22 232333 1818 2244 262655 3366 4477 11

TotalTotal 18831883 742742 5454 266266


Frequency of Compound ExpressionsFrequency of Compound ExpressionsWithin ComponentWithin ComponentOccurrenOccurrence ce

FrequencyFrequency

AnyAny Periods Periods (.)(.)

^̂ ++ //

11 13901390 14901490 726726 5252 24124122 691691 271271 1616 22 232333 101101 1818 2244 1313 262655 2626 3366 88 4477 22 1188 33

TotalTotal TotalTotal 18831883 742742 5454 266266


Some Components with two ^ separatorsSome Components with two ^ separators DIFFUSION CAPACITY.CARBON MONOXIDE^^DIFFUSION CAPACITY.CARBON MONOXIDE^ÂDJUSTED FOR ADJUSTED FOR

HEMOGLOBINHEMOGLOBIN DIFFUSION CAPACITY^^DIFFUSION CAPACITY^ÂDJUSTED TO BODY CONDITIONSADJUSTED TO BODY CONDITIONS TIDAL VOLUME.EXPIRED.SPONTANEOUS^^TIDAL VOLUME.EXPIRED.SPONTANEOUS^ÛNCORRECTED FOR UNCORRECTED FOR

COMPRESSIBLE GAS VOLUME.SETTINGCOMPRESSIBLE GAS VOLUME.SETTING TIDAL VOLUME.EXPIRED.SPONTANEOUS^TIDAL VOLUME.EXPIRED.SPONTANEOUSÔN ON

VENTILATORVENTILATOR^CORRECTED FOR COMPRESSIBLE GAS VOLUME^CORRECTED FOR COMPRESSIBLE GAS VOLUME TIDAL VOLUME.SPONTANEOUS+MECHANICAL^TIDAL VOLUME.SPONTANEOUS+MECHANICALÔN ON

VENTILATORVENTILATOR^CORRECTED FOR COMPRESSIBLE GAS VOLUME^CORRECTED FOR COMPRESSIBLE GAS VOLUME TIDAL VOLUME.SPONTANEOUS+MECHANICAL^TIDAL VOLUME.SPONTANEOUS+MECHANICALÔN ON

VENTILATORVENTILATOR^CORRECTED FOR ^CORRECTED FOR COMPRESSIBLE GAS COMPRESSIBLE GAS VOLUME/BODY WEIGHTVOLUME/BODY WEIGHT

TIDAL VOLUME.SPONTANEOUS+MECHANICAL^TIDAL VOLUME.SPONTANEOUS+MECHANICALÔN ON VENTILATORVENTILATORÛNCORRECTED FOR COMPRESSIBLE GAS VOLUMEÛNCORRECTED FOR COMPRESSIBLE GAS VOLUME

VOLUME^VOLUMEÂT 1.0 S POST FORCED EXPIRATIONAT 1.0 S POST FORCED EXPIRATION^̂POST POST BRONCHODILATIONBRONCHODILATION

VOLUMEÂT 1.0 S POST FORCED EXPIRATION^PRE VOLUMEÂT 1.0 S POST FORCED EXPIRATION^PRE BRONCHODILATIONBRONCHODILATION

VIEWS^W CONTRAST.VIEWS^W CONTRAST.XXX TRANSHEPATICXXX TRANSHEPATIC^̂W HEMODYNAMICSW HEMODYNAMICS


Some Components with five . SeparatorsSome Components with five . Separatorsand one with sixand one with six CAPACITY.VITAL.FORCED.POST CAPACITY.VITAL.FORCED.POST

BRONCHODILATIONBRONCHODILATION/CAPACITY/CAPACITY.VITAL.FORCED PREDICTED.VITAL.FORCED PREDICTED VOLUME.AT 25-75% OF FORCED VOLUME.AT 25-75% OF FORCED

EXPIRATION.MEASURED.POST EXPIRATION.MEASURED.POST BRONCHODILATIONBRONCHODILATION/VOLUME/VOLUME.AT 25-75% OF FORCED .AT 25-75% OF FORCED EXPIRATION.PREDICTEDEXPIRATION.PREDICTED

VOLUME.AT 25-75% OF FORCED VOLUME.AT 25-75% OF FORCED EXPIRATION.MEASURED.PRE EXPIRATION.MEASURED.PRE BRONCHODILATIONBRONCHODILATION/VOLUME/VOLUME.AT 25-75% OF FORCED .AT 25-75% OF FORCED EXPIRATION.PREDICTEDEXPIRATION.PREDICTED

BLOOD FLOW.MAX.BLOOD FLOW.MAX.STENOSISSTENOSIS.INTERNAL CAROTID .INTERNAL CAROTID ARTERYARTERY/BLOOD FLOW.MAX./BLOOD FLOW.MAX.UNOBSTRUCTEDUNOBSTRUCTED.COMMON .COMMON CAROTID ARTERYCAROTID ARTERY


Hasty generalizationsHasty generalizations The sub-syntax of clinical LOINC name The sub-syntax of clinical LOINC name

components is complex (.^+/)components is complex (.^+/) Composition syntax is wildly inconsistentComposition syntax is wildly inconsistent Parsing these puppies may mandate a call Parsing these puppies may mandate a call

to the SPCA – not prettyto the SPCA – not pretty


On ontologiesOn ontologies There do not appear to be consistent sets There do not appear to be consistent sets

of terms from which clinical LOINC names of terms from which clinical LOINC names are composedare composed Anatomy, timing, setting, adjustmentsAnatomy, timing, setting, adjustments

There do not appear to be consistent sub-There do not appear to be consistent sub-axes within complex component namesaxes within complex component names


So, What does Chris want done about it?So, What does Chris want done about it?

Not a simple or easy problemNot a simple or easy problem We must solve information/terminology We must solve information/terminology

model boundary problemmodel boundary problem Exemplar issue of sub-message boundaryExemplar issue of sub-message boundary

TemplateTemplate Archetype Archetype CEM (Clinical Expression Module)CEM (Clinical Expression Module)


Once the miracle occursOnce the miracle occurs(model boundaries agreed upon)(model boundaries agreed upon)

Clinical LOINC would be well advised toClinical LOINC would be well advised to Recognize it is not analogous to lab test name Recognize it is not analogous to lab test name

structures (no Silver book master)structures (no Silver book master) Have a terminology RIMHave a terminology RIM Entertain DMIMsEntertain DMIMs

Where truncation of element implies aggregationWhere truncation of element implies aggregation Define terminology tables to populate slotsDefine terminology tables to populate slots

Hierarchies which support aggregation Hierarchies which support aggregation


On syntaxOn syntax The 6-part model may not be optimal for such The 6-part model may not be optimal for such

complex expressionscomplex expressions DMIMs imply variable size and shape of DMIMs imply variable size and shape of

componentscomponents Use of delimiters (.^+/) should be rigorously Use of delimiters (.^+/) should be rigorously

consistent or abandonedconsistent or abandoned And/or must always aggregate by truncationAnd/or must always aggregate by truncation

Perhaps will require XML or OWL structures Perhaps will require XML or OWL structures


Historical analog Historical analog HL7 V2 was simple, spare, and usableHL7 V2 was simple, spare, and usable V2 did not scale well to complexity of clinical V2 did not scale well to complexity of clinical

enterpriseenterprise Consistent and comparable messages are not Consistent and comparable messages are not

dependable among V2 implementationsdependable among V2 implementations V3 imposes more rigorous formalisms to achieve V3 imposes more rigorous formalisms to achieve

comparable and consistent information comparable and consistent information interchangeinterchange


Clinical LOINC (and other variants)Clinical LOINC (and other variants) It may be time to consider “V3” style re-It may be time to consider “V3” style re-

casting of the venerable LOINC structurecasting of the venerable LOINC structure A formal, subset-able, terminology model A formal, subset-able, terminology model

may be desirable may be desirable One may chose to invoke Description Logic One may chose to invoke Description Logic

formalisms within element hierarchiesformalisms within element hierarchies Syntax should evolve to correspond Syntax should evolve to correspond

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