Intensional Value Set Definitions Referencing LOINC Formal Names for Axes (and other Parts) for use in defining Value Sets Ted Klein August 29, 2013

Intensional Value Set Definitions  Refer to collections of codes in code systems  E.g. the SNOMED CT concept Tuberculosis (disorder) and all of its subconcepts  The concept relationships ‘Generalizes’ and ‘Specializes’ have been implemented in HL7 Value Set machinery  HL7 has also used the notion of a code system ‘Property’ with an optional value to indicate other kinds of collections  Terminologes are assumed to have various properties  These properties can be identified by their name in the published terminology –E.g. in SNOMED CT, conceptProperty name=“Pathological process” value=“ Infectious process (qualifier value)” –Any kind of singular or relationship property should be supported 2

Formal Names  IHTSDO Publishes the names of properties in SNOMED CT  Defined in the SNOMED CT concept model  Folks are using these published names as the formal names for value set definitions  People want to do similar things in LOINC  Done ad-hoc currently  For other terminologies such as ISO Health informatics - Point-of-care device codes there are some value sets with definitions like “Restricted to ECG Category Names”  There is a strong desire at HL7 to develop a standard for this, or at least a widely agreed set of policies –Document Ontology group has an immediate need for such value sets for their September ballot opening  We believe that a terminology should specify how this should be done for that terminology 3

Current State  Folks are currently doing things in an ad-hoc way  HL7 has a value set which has a defining expression “All LOINC codes WHERE class = doc.section”  “Others are asking how to do similar things –LOINC codes where SYSTEM is a specific list of values, All METHOD codes, etc.  We really need to agree on a policy for how folks should do this for LOINC  The official names for things need to be clear in the LOINC manual also! 4

Options  Use the names from the LOINC manual for the axes?  Are the names of the axes identical in all documentation?  Should they be always only uppercase?  Use the LP (loinc part) codes for the axes?  Not clear due to how the display is shown in RELMA on a loinc part search for the parts that are the axis names  What about other things?  Hierarchy relationships  What to do about null values in some axes such as Method?  What about wild cards?  What is the best approach to solve this? 5