Best Practices for Interoperable Data Exchange Using LOINC

Report
Best Practices for Interoperable
Data Exchange Using LOINC
Ming-Chin (Mark) Lin, MD
Stanley M. Huff, MD
Introduction
• 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
Introduction (continued)
• 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?
Introduction (continued)
• 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?
Principles/Goals in Choosing Best
Practices
• 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
Approach
• 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
Proposed Process
• 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)
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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.
Proposal #1
Request a new code when
analyte/component details don’t
match LOINC exactly
Examples
• 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.
Proposal #2
Always send method information as
an independent element in the OBX
segment.
“Fit for Purpose” or “Good Enough”
mapping versus “Best Practice”
• 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
Proposed Best Practice
• 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
Examples
• Local test: Hepatitis C virus Ab.IgG by EIA
• 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|…||…
Proposal #3
Always map to the Quantitative code
even if the lab is only sending the
interpretation.
Proposed Best Practice
• 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
Examples
• 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||||
Discussion
Degrees of Interoperability
• 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
Degrees of Interoperability (cont)
• 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
Similar EDs should have similar LOINC codes,
different LOINC codes mean inconsistency.
Source
Examples of EDs
A
[Local name]: Alpha 1 antitrypsin phenotyping
[LOINC®]: 6770-2: Alpha 1 antitrypsin phenotyping:
Immunofixation: Prid: Pt: Nom: Ser/Plas
[Coded Variables and their frequencies]: M1M1 (75), M1M2 (31),
M1S (12), MM (8), M1Z (6)
B
[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)

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