Ming-Chin (Mark) Lin, MD
Stanley M. Huff, MD

• Two primary use cases
– Sharing data between and among different institutions for patient care
– Aggregating data between and among different institutions for clinical research, quality improvement, public health surveillance, etc.
(secondary use)
• Use LOINC codes as the lingua franca for the data sharing

• Mark’s work comparing LOINC usage across ARUP,
Regenstrief, and Intermountain
• What is truth?
– If local codes from different sites are mapped to the same LOINC code, how do we know they are really the same test?
– If local codes from different sites are mapped to different LOINC codes, how do we know they are really different tests?
• Extensional definitions
– Comparison of names (substance, timing, property, specimen), units of measure, mean value, standard deviation, coded values, co-occurring tests, etc.
• Results: We found about a 4% error rate in mapping
– And that is us! What is it like for “regular” facilities?

• Analyzing the errors lead to additional questions
– Can we classify the errors?
– What is the ultimate goal of mapping?
– Can we define “best practices” for mapping so that everyone doing mapping can achieve greater accuracy?

• Optimize for patient safety, interoperability, and secondary use of data
• Anticipate change - Make the process as easy as possible when new codes are created, technology changes, or when errors are corrected
• Make the practices understandable and reproducible
• Have the least possible impact on LOINC staff

• State best practices to encourage movement to better processes
• We expect this to take time
• Don’t try to mandate anything (we don’t have any authority to do that)
• Not following best practices is not considered
“non compliance” to standards
• We may need to change some LOINC content to better support best practices

• Create specific best practice guidelines for difficult situations and common errors
• Consider a few questions each meeting
• As agreements are made, add the best practices as a section in the LOINC manual
• Example issues (please contribute your issues)
– Specificity of analytes
– Best approach for sending method specific data
– Best practice for value of quantities and interpretations
– How to deal with pre and post coordinated specimen type
– How to deal with pre and post coordinated challenge conditions
– Use of Acnc and Titr
– Etc.

Request a new code when analyte/component details don’t match LOINC exactly

• A new local test is for Avian pox virus Ab.IGG
– Not a match for Avian pox virus Ab
• A new local test is for Avian paramyxovirus 10 Ab
– Not a match for Avian paramyxovirus Ab
• A new local test for 11-Deoxycortisol.free SCnc
– Not a match for 11-Deoxycortisol SCnc
• Many, many examples where there is a parent-child relationship between items. These are never a match. Always request a new code.

Always send method information as an independent element in the OBX segment.

• Example: Tests where the name includes a specific method at site A are mapped to methodless tests at site B
• Works for the known use case
– Either estimated weights or scale weights may be good enough for a particular study
• This represents a loss of information when data moves from A to B

• Always capture the method with the data if it is known
• Best practice: Always map to the methodless
LOINC code but always send the method as part the value of OBX.17 Observation Method
• Related policy: The LOINC Committee will encourage and help develop a coded value set for methods
• Allowed practice: Map to the LOINC code that precoordinates the method in the code
• Discouraged practice: mapping tests where the method is known to methodless LOINC codes

• Best: send EIA as method in OBX
– OBX|1|CE| 16936-7 ^ Hep C virus ^ LN |…|EIA|…
• Allowed: Send precoordinated code for EIA method
– OBX|1|CE| 57006-9 ^ Hep C virus EIA ^ LN |…||…
• Discouraged: Method not sent
– OBX|1|CE| 16936-7 ^ Hep C virus ^ LN |…||…

Always map to the Quantitative code even if the lab is only sending the interpretation.

• Always map to the quantitative LOINC code
– Related policy: The LOINC Committee will discourage or deprecate the use of nominal or ordinal LOINC codes for concentrations
• Send numbers when they exist as the value of
OBX 5
• Send interpretations when they exist as the value of OBX 8
• One or the other or both of the numeric value and the interpretation can exist in a data instance

• Local test: Cocaine in blood, with values of “positive” and “negative”
• Best: Map to Cocaine Qn and send interpretive value in OBX.8
(Interpretation, was previously abnormal flag)
• OBX|1|CE| 72405-4 ^ Cocaine MCnc Bld Qn ^ LN |||||positive|
• Anticipates future send of value and interpretation
• OBX|1|CE| 72405-4 ^ Cocaine MCnc Bld Qn ^ LN ||4.0|ng/ml||positive|
• Discouraged: Map to ACnc Ord and send interpretation in OBX.5
• OBX|1|CE| 16633-0 ^ Cocaine ACnc Bld Ord ^ LN ||positive||||

• Degree I: Exact equivalence without translation
– Same code, unit of measure, and value set
– Data are mutually substitutable in all contexts of use
• Degree II: Exact equivalence after translation
– Unit of measure conversion (need UCUM)
– Mass concentration to substance concentration conversion
(need the molecular weight)
– Pre and post coordination translation
• Method as part of LOINC code versus method sent somewhere else in the message
• Peak or trough as part of LOINC code versus peak and trough sent somewhere else in the message
– Data are mutually substitutable in all contexts of use after translation

• Degree III: Context specific subsumption
– A parent-child relationship exists between tests at the different institutions
• Method specific tests roll up to methodless tests
• IgM or IgG antibodies roll up to generic antibody
– Data are mutually substitutable only in a specific
context of use even after translation
• Degree IV: No interoperability
– No comparable data or information exists between or among institutions

Source
Similar EDs should have similar LOINC codes, different LOINC codes mean inconsistency.
Examples of EDs
A [Local name]: Alpha 1 antitrypsin phenotyping
[LOINC®]: 6770-2 : Alpha 1 antitrypsin phenotyping:
Immunofixation: Prid : Pt: Nom: Ser/Plas
B
[Coded Variables and their frequencies]: M1M1 (75), M1M2 (31),
M1S (12), MM (8), M1Z (6)
[Local name]: Alpha 1 antitrypsin phenotyping
[LOINC®]: 32769-2 : Alpha 1 antitrypsin phenotyping :
No method: Imp : Pt : Nom : Ser/Plas
[Coded Variables and their frequencies]: M1M1 (887), M1M2 (278),
M1S (91), M1Z (88), MM (86), SEE NOTE (60)