The Future of NDC:The HL7 Perspective
James J. Cimino, M.D.
Co-chair, HL7 Vocabulary Technical Committee
Departments of Medicine and Medical Informatics
Columbia University College of Physicians and Surgeons
Outline
• HL7’s Needs
• Desiderata– Summary of 10+ years of research on
controlled medical terminologies– Presented at IMIA Working Group 6,
Jacksonville, FL, 1997
• NDC and the Desiderata
• HL7’s Perspective of NDC
HL7 Needs Drug Codes to...
…transfer medication orders from an order entry system to a pharmacy
…aggregate data from multiple sources
…serves as grist for decision support engines
…just about anything else you can imagine
Drug Model Hierarchy
Drug Class
Not-Fully-Specified Drug
Clinical Drug
Trademark Drug
Manufactured Components
Ingredient Class
International Package Identifiers
Country-Specific Packaged Product
Ingredient
is-a
is-a
is-a
is-a
is-a
is-a
Chemicals
MedicationsPackages
Composite Clinical Drug
is-a
Composite Trademark Drug
is-a
Drug Model Hierarchy
Drug Class
Not-Fully-Specified Drug
Trademark Drug
Manufactured Components
Ingredient Class
International Package Identifiers
Country-Specific Packaged Product
Ingredient
is-a
is-a
is-a
is-a
is-a
is-a
Chemicals
MedicationsPackages
Composite Clinical Drug
is-a
Composite Trademark Drug
is-a
Clinical Drug
Clinical Drugs
• Dosage form
• Active ingredients– Chemical
– Form Strength• Strength amount
• Strength units
• Volume
• Volume units
Concept Orientation
• Unique identifiers associated with meaning
• Name can change; meaning cannot
• Nonredundant
• Unambiguous
• Codes can’t be reused
Polyhierarchy
Empirin #3
Aspirin 325/Codeine 30mg
Tablet
Aspirin Preparations
Codeine Preparations
Opiate Analgesic
Nonsteroidal Anti-inflammatory
Medication
Glaxo Wellcome Products
Tablet
Formal Definitions
• Avoid misunderstanding of meaning
• Allow detection of ambiguity and redundancy
• Support multiple classification
Formal Definitions
(Empirin #3:
(Ingredients:
( (Ingredient Aspirin) (Strength “325”) (Units milligrams) )
( (Ingredient Codeine) (Strength “30”) (Units milligrams) )
(Form: Tablet)
(Manufacturer: Glaxo Wellcome) )
Reject “Not Elsewhere Classified”
• Ambiguous (e.g., “Other Antibiotics”)
• Semantic drift thwarts concept permanence
Multiple Granularities
Empirin #3
Aspirin 325/Codeine 30mg
Tablet
Nonsteroidal Anti-inflammatory
Medication
Aspirin Preparations
Graceful Evolution• Support:
– Simple addition– Refinement– Minor name changes– Precoordination– Disambiguation– Obsolescence– Discovered redundancy
• Avoid:– Redundancy– Major name changes– Code reuse– Changed codes
NDC and the Desiderata• Content - timeliness and comprehensiveness• Concept orientation - done• Concept permanance - needs work• Nonsemantic identifiers - worst of both worlds• Polyhierarchy - may be beyond purview of FDA• Formal definitions - easily accomplished• Reject “NEC” - done (watch out for hierarchies)• Multiple granularities - as per polyhierarchy• Graceful evolution - editorial policy needed