The Future of NDC: The HL7 Perspective James J. Cimino, M.D. Co-chair, HL7 Vocabulary Technical Committee Departments of Medicine and Medical Informatics.

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

Content

• Needs to be complete

• Needs to be up-to-date

Concept Orientation

• Unique identifiers associated with meaning

• Name can change; meaning cannot

• Nonredundant

• Unambiguous

• Codes can’t be reused

Concept Permanence

• Meaning doesn’t change

• Never deleted

Nonsemantic Identifiers

• Don’t use names

• Don’t use mnemonics

• Don’t use hierarchical codes

Polyhierarchy

• Multiple classes for terms

• Multiple views

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) )

NEC

Reject “Not Elsewhere Classified”

• Ambiguous (e.g., “Other Antibiotics”)

• Semantic drift thwarts concept permanence

Multiple Granularities

• Different users need different abstractions

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

HL7’s Perspective

• Need unique identifiers for:– Clinical (orderable) products– Dispensable products– Classes– Drug forms– Delivery routes

• Need all these in a timely, high-quality form

• Not all need come from FDA