Controlled Medical Nomenclature for NAHLN NAHLN January 2005 Las Vegas, NV

Qualifications There’s “retentive” – if that’s not enough: There’s “anal retentive” – if that’s not enough: There’s “retentive enough to create and maintain a nomenclature”

Lists of words… Nomenclature The system or set of names for things, etc., commonly employed by a person or community (Petchamp, SNVDO, SNOMED) The system or set of names for things, etc., commonly employed by a person or community (Petchamp, SNVDO, SNOMED)Vocabulary A collection or list of words with explanations of their meanings (SNOMED) A collection or list of words with explanations of their meanings (SNOMED)Classification The result of classifying; a systematic distribution, allocation, or arrangement, in a class or classes; esp. of things which form the subject-matter of a science or of a methodic inquiry. (SNOMED) The result of classifying; a systematic distribution, allocation, or arrangement, in a class or classes; esp. of things which form the subject-matter of a science or of a methodic inquiry. (SNOMED)

What do we need? Nomenclature ONLY Provides a simple list for data entry Provides a simple list for data entry Vocabulary / Classification We can be CERTAIN that the “term” (description in SNOMED) means what we think it means. We can be CERTAIN that the “term” (description in SNOMED) means what we think it means. We can develop rules that allow us to combine concepts to express ideas more complicated than those contained in the nomenclature. We can develop rules that allow us to combine concepts to express ideas more complicated than those contained in the nomenclature. We can use the knowledge base supported by the vocabulary/classification to search, retrieve and analyze our data. We can use the knowledge base supported by the vocabulary/classification to search, retrieve and analyze our data.

NAHLN Nomenclature needs Is controlled nomenclature (1 or more) essential – YES Is LOINC essential – Yes (or something close) Is SNOMED essential – NO, but you need standard microorganisms, breed/species, etc. Can SNOMED provide what’s needed outside of laboratory tests - YES

Why a controlled nomenclature? Aggregation of text-based content from multiple sources Multiple individuals Multiple individuals Multiple institutions Multiple institutions Any time you rely on a computer to manipulate language and “meaning” is critical. Procedures list (for billing) Procedures list (for billing)

Why a controlled vocabulary / nomenclature? Bovine respiratory disease complex = Shipping fever = BRDC How does one automate recognition of the synonymy?

Why did “we” pick SNOMED? A shared nomenclature must be maintained. SNOMED is the ONLY actively maintained nomenclature that has veterinary content. AVMA had a long-term investment Veterinary medicine CANNOT afford: To build it’s own competent nomenclature To build it’s own competent nomenclature To continue to live without a competent nomenclature To continue to live without a competent nomenclature

Characteristics of a controlled vocabulary / nomenclature. Cimino, JJ. Desiderata for Controlled Medical Vocabularies in the Twenty- First Century Methods of Information in Medicine Nov, 37(4-5): THE Review of ideal characteristics of a controlled medical vocabulary / nomenclature. Perhaps the best READING review of medical vocabulary / nomenclature available.

Content, content, content First criticism of ANY nomenclature (by users) is lack of content

Content, content, content Approaches Enumerate all possible concepts (simple and complex) Enumerate all possible concepts (simple and complex)Pneumonia Pneumonia of left lung Pneumonia of left caudal lung This nomenclature will grow quickly. It will get VERY large VERY fast.

Content, content, content Approaches Enumerate all possible concepts (simple and complex) Enumerate all possible concepts (simple and complex) Provide all necessary “atoms,” create effective syntax, “teach” the syntax to users (or systems). Provide all necessary “atoms,” create effective syntax, “teach” the syntax to users (or systems).Pneumonia Left lung Left Caudal lung Pneumonia Pneumonia, body part (left lung) Pneumonia, body part (left caudal lung) Probably the theoretical ideal. I have not the first idea how!

Content, content, content Approaches Enumerate all possible concepts (simple and complex) Enumerate all possible concepts (simple and complex) Provide all necessary “atoms,” create effective syntax, “teach” the syntax to users (or systems). Provide all necessary “atoms,” create effective syntax, “teach” the syntax to users (or systems). Drastically limit the scope of the nomenclature. Drastically limit the scope of the nomenclature. May actually improve usability of the nomenclature for a limited purpose, however: 1. The next project and the next interaction require development of a new nomenclature 2. Connections between projects require “mapping”. 3. Users will not be happy. Might be easier to build and use a large single nomenclature.

Concept Orientation Concept – an embodiment of a particular meaning Concepts must correspond to at least one meaning (non-vagueness) Concepts must correspond to at least one meaning (non-vagueness) Concepts must correspond to no more than one meaning (non-ambiguity) Concepts must correspond to no more than one meaning (non-ambiguity) Meanings correspond to no more than one concept (non-redundancy) Meanings correspond to no more than one concept (non-redundancy)

Concept permanence Once created, the meaning of a concept is inviolable. Concept identifiers can NEVER be reused. Contributes to stability of legacy information. Contributes to stability of legacy information.

Non-semantic identifier Unique name Using the name inhibits (prohibits?) improvements in concept “name” Using the name inhibits (prohibits?) improvements in concept “name” Harder to cope with synonymy. Harder to cope with synonymy. Hierarchical designators (codes with meaning) inhibit classification Monohierarchies provide inadequate classification capability for retrieval purposes. Monohierarchies provide inadequate classification capability for retrieval purposes. Polyhierarchies cannot be supported. Polyhierarchies cannot be supported. (A concept can’t be in its multiple logical locations).

Polyhierarchies Medical concepts often classified in multiple ways Acute bacterial pneumonia It is a bacterial (infectious) disease It is a bacterial (infectious) disease It is a pulmonary disease It is a pulmonary disease It is an inflammatory condition It is an inflammatory condition It is an acute condition It is an acute condition

Formal definitions Collection of relationships to other concepts in the vocabulary Acute Bacterial pneumonia Causative agent = bacteria Causative agent = bacteria Has location = lung Has location = lung Has morphology = inflammation Has morphology = inflammation Has course = acute Has course = acute

Reject “not elsewhere classified” The fundamental problem is “meaning drift” Example Year one nomenclature has Year one nomenclature hasPneumoniaBronchitis Respiratory disease NEC

Reject “not elsewhere classified” The fundamental problem is “meaning drift” Example Year TWO the nomenclature has Year TWO the nomenclature hasPneumoniaBronchitisTracheobronchitis Respiratory disease NEC Last year tracheobronchitis was “respiratory disease, NEC”

Reject “not elsewhere classified” (NEC) NEC ≠ NOS (Not Otherwise Specified) NOS = “I’ve said all I’m going to say”. NOS = “I’ve said all I’m going to say”. NOS is not considered to be inappropriate. NOS is not considered to be inappropriate. Current preference is to exclude NOS. The concept means what it means, no more no less. Current preference is to exclude NOS. The concept means what it means, no more no less.

Multiple granularities A large standardizing nomenclature (like SNOMED) must provide concepts at an appropriate level of detail for every user class. Not an issue with a purpose-built nomenclature.

Recognize Context Must provide an ability to distinguish between uses of the concept… Patient has acute bacterial pneumonia Patient has acute bacterial pneumonia Patient has history of acute bacterial pneumonia Patient has history of acute bacterial pneumonia Patients littermate died of acute bacterial pneumonia Patients littermate died of acute bacterial pneumonia System design and perhaps the message system should cope with acquiring context Nomenclature may be required to cope with context in messages, or may provide context concepts for the message.

Evolve Gracefully A nomenclature must have a strategy for coping with new content. The bane of home grown nomenclatures The bane of home grown nomenclatures (Who’s looking after your list of concepts?) Nomenclature maintenance is not everyone’s cup of tea. Nomenclature maintenance is not everyone’s cup of tea. A controlled nomenclature serves as an arbiter of sorts. A controlled nomenclature serves as an arbiter of sorts. A nomenclature used by more than one organization (d-lab) must have update and sharing mechanisms in place.

Recognize redundancy Redundancy must be avoided in the concept list Redundancy must be provided for using a synonym mechanism. Egos and dispersed training insure that there exist multiple ways to say almost anything. They’re still talkin’ about the same thing. They’re still talkin’ about the same thing.

SNOMED history / future Reduce storage size Reduce Storage size No longer relevant Categorize information Multiple code-based hierarchies Poly-hierarchical categorization Pathology content “All Medicine” Veterinary content separate, then integrated Integrated content “Computability” for retrieval. Natural language, artificial intelligence, decision support SNOP SNOMED SNOVET SNOMED III SNOMED RTSNOMED CT

Development history SNOP Morphologies MorphologiesSNOMED Morphologies, Etiologies, Locations Morphologies, Etiologies, LocationsSNOVET Same structure as SNOMED Same structure as SNOMED Mix of existing SNOMED, additional veterinary content Mix of existing SNOMED, additional veterinary content SNOMED III Disorders, Morphology, Living organisms, social context Disorders, Morphology, Living organisms, social context Veterinary content re-integrated Veterinary content re-integrated SNOMED RT Logic based approach to SNOMED. Axes became hierarchies. Most significantly, the poly-hierarchic approach to classification. Logic based approach to SNOMED. Axes became hierarchies. Most significantly, the poly-hierarchic approach to classification. SNOMED CT SNOMED RT on steroids. Post merger with CTv3. SNOMED RT on steroids. Post merger with CTv3.

SNOMED III (3.5) A – Physical agents C – Chemicals D – Disease F – Biological function G – General qualifiers J - Jobs L – Living organisms M – Morphology P – Procedures S – Social context T – Topography X – Pharmaceutical companies Axes

SNOMED CT Disease Finding / observation / clinical history Procedure Body structure normal and abnormal Organism Physical Force SubstanceSpecimen Social Context Attributes Context dependent categories Physical object Events Environments and geographical location Observable entity Qualifier value Staging and Scales

Complaints about SNOMED It’s too… Big Big Complicated Complicated Expensive Expensive Yes but… We can make it smaller (sort of), and use small pieces (for most purposes). We can make it smaller (sort of), and use small pieces (for most purposes). Use it in simple and straightforward ways Use it in simple and straightforward ways But nothin, it’s a bit expensive. But nothin, it’s a bit expensive. Not the license fees, the cost of making it work.

Is the expense worth it? IF the long-range goal is useful… The selected standards adhere to design specifications that have developed through hard experience in the medical profession. The selected standards adhere to design specifications that have developed through hard experience in the medical profession. Essential / desirable features have been documented. The selected standards represent extraordinary functionality, produced and maintained at great cost to the medical profession. The selected standards represent extraordinary functionality, produced and maintained at great cost to the medical profession. We can leverage these standards for 10¢ / $1.00

Bovine reportable disease system. Bovine breeds Bovine “occupation” and husbandry concepts Brief list of reportable diseases Lab tests that support disease list Place to put the concepts in the message structures Lab to network Lab to network

Bovine medical record Bovine Breeds Bovine lab tests, all not just reportable All applicable disorders, findings, procedures Message structures lab to clinic lab to clinic clinic to lab clinic to lab clinic to clinic clinic to clinic

SNOMED-CT, HL-7, LOINC Mixed practice Subsets of standards Bovine practice Bovine disorders Bovine Reportable

WNV Rabies FMD SNOMED 1 LOINC 1 HL7 2 Disease reporting system 1 = three independent subsets 2 = one subset of necessary messages