8 - Evolving principles for naming collections

8.1 Goals and general approach

We are in the process of evolving our model for naming collections in LOINC. Our goals in refining this model are to:

  • Create names that are consistent across different subject domains within LOINC
  • Make it easy to create a list of all codes that could be used as document type in CDA
  • Make it easy to create a list of all codes that could be used as section headings in CDA
  • Avoid proliferating names

To this end, we are developing rules for how the naming of collections will apply to both laboratory collections (CBC, CHEM7) coded and structured clinical collections (Vital Signs), documents (Admit History and Physical Exam), Apgar scores, Braden Scale, Pain scales, etc. There will be two categories of names for collections:

  • Names for panels with enumerated discrete contents, and
  • Names for general collections of information.

Using the existing panel mechanisms, the LOINC database will record the association between LOINC collections and individual observations where these associations are known. For example, LOINC already records the expected contents for CBC, Liver Enzymes, etc. It will also include definitions for Vital Signs, Cardiac Catheterization, Braden Scale, surveys, etc. We will create a single LOINC code for any general collection of information where the information content of the collection is the same, regardless of whether the content is a text document, a scanned image of text, or a sound file of the same information.

Since collections are named by their real or anticipated contents, the same LOINC code could be used as either a document type or as a section type.

8.2 Collections as orders and observations

The same LOINC code will be used for ordering a procedure, naming the document produced as the description of the procedure, or naming the structured and coded set of observations from the procedure.

For panels, the same code for CBC would be used as the ordered item in an order record or message, and as the panel identifier in the OBR segment of a result record or message. The same pattern would be followed for laboratory procedures and clinical procedures.

For general collections, the same code would be used as the ordered item in an order record or message, and as the result identifier in a result message. For example, the general collection name could be used in a result message as the identifier of a document type, as a section label, as the universal identifier in an OBR segment, or as the identifier in an OBX segment depending on the circumstances. The same pattern would be followed for radiology procedures and clinical procedures.

We are not taking away the flexibility of having the ordered code be different from the result code. For example, it is often desirable for the order code to be less specific and more abstract than the result code. LOINC would contain codes for something like “Exercise EKG” with the expectation that the result could come back as “AHA Protocol Stress EKG Result”. The point is that, when appropriate, we would use the same LOINC code in the contexts of orders and results. We would NOT make LOINC codes that meant “CBC Order” and “CBC Result”. Rather, we would use the same LOINC code for CBC in both orders and results.

Current practice would also continue where a “pure” procedure is ordered and discrete results would be returned. For example, Urine Microscopic Exam could be ordered and discreet values for cell types, casts, amorphous material, etc. would be returned.

8.3 LOINC Scale for collections

Where the Scale for individual elements in a panel vary, the name of the panel term itself will be a dash (-). The Scale for general information collections will be Doc, short for document, which is used in the most general sense of a text document, image, scanned text image, etc. We are in the process of reviewing our current use of Nar (narrative) or Nom (nominal) for general information collections in some portions of the LOINC database and migrating towards broader use of Doc. We have already made such changes in some areas, for example Radiology and Molecular Pathology.

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