December 10, 2002 Eric Rose, MD 1

Home-Grown Coding Systems—A Critical Step in EMR Implementation

Eric Rose, MDAssociate Director for Clinical InformaticsInformation Systems DepartmentUniversity of Washington Physicians Networkhttp://faculty.washington.edu/momus/

December 10, 2002 Eric Rose, MD 2

SUMMARY

Implementation of any EMR (including vendor-supplied) requires the that the user institution create coding systems

This can be done well or badly It matters

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Some definitions

Concept: an idea encompassing a class of objects ("unit of knowledge created by a unique combination of characteristics"-ISO)

Term: A word denoting a concept Terminology/Controlled Vocabulary/Ontology: a

set of terms pertaining to a given domain, not necessarily with any structure

Nomenclature: A terminology “structured systematically according to pre-established naming rules” (ISO)

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Coding system: A terminology + context-free symbolic codes for each term

Classification/taxonomy: A terminology system + specified relationships between terms (“concept system”-ISO 1087-1)

Some definitions (cont’d)

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What is a coding system and what does it do? Represents in a standardized

fashion Groups Separates Abbreviates Facilitates automated data-

processing & transmittal

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Types of coding systems Simple, 1-1 (CA, NY, TX) Categorical (record store bins) Hierarchical (homo sapiens) Multiaxial (Dewey-decimal,

SNOMED)

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What does this have to do with EMR Implementation?

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LOINC

SNOMEDCT

ICD-10

CPT

ICD-9-CM

READ

NCPDP

NDC

NANDA

THE UNIVERSE OF CONCEPTS

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What does this have to do with EMR Implementation?

Most EMR’s allow customized choices for various database items

Each one of these is a small coding system

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If developed carefully, home-grown coding systems facilitate: Intuitive data entry Interpretable data @ individual

patient level Usable data at population level Usable data for automated

decision-support systems Data that is shareable with other

systems

What does this have to do with EMR Implementation? (cont’d)

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Examples of mini-coding systems you might need to create

Disease Categories for Family History

Reason for Visit Allergic Reaction Type Delivery Outcome Anesthesia Type for Surgery Source of Diagnostic Specimens Ethnic Group Marital Status

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What makes a coding system good? Completeness Nonredundancy Clarity Stability Granularity appropriate to use or

flexible Evolutionary

(Adapted from Cimino, 1998; Chute et al., 1998)

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Completeness

There should be a term for any possible situation

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Completeness—ExampleReason for Medication Discontinuation

Allergic responseAlternate therapyAvailabilityCost of medicationDiscontinued by another Health Care ProviderDiscontinued by patientDose adjustmentDuplicateErrorIneffectiveNON Covered MedicationParadoxical responsePregnancyPrescription never filledReorderResistant OrganismSide effectsTherapy completed

What if medication was never taken by patient? No way to denote that!

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Nonredundancy

There should be only one term for any given situation

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Nonredundancy-ExampleNext of Kin-Relationship to patient

Domestic Partner

Life Partner

Partner

Significant Other

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Clarity

The categories in your coding system should be unambiguous to all users

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Clarity-Examples

Family Medical History category “Blood Disease,” “Anesthesia”

Medication reason-for-d/c “Alternative Therapy,” “Error”

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Stability

Once defined, the meaning of a code must not be changed, though it may be inactivated so it is not applied to any new cases

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Appropriate or Flexible Granularity

Granularity = Level of detail described by the coding system, i.e. “fineness” of categorization

Low granularity = Few, broad categories

High granularity = Many, narrow categories

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Appropriate Granularity-ExamplesFamily History categories

“Alcohol dependency,” “Drug dependency”—It is sufficient to just have one category for “Chemical Dependency”

“Heart disease”-Not granular enough to meet needs of risk assessment for coronary disease

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Evolutionary

Coding system development is an ongoing process, requiring addition of new categories and inactivation of old ones to keep the system congruent with prevailing ideas.

Example = Family History category, “Venous Thrombosis”

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Guiding principles CENTRALIZE control of the coding

system Keep your lists SHORT Respond PROMPTLY to user

requests for additions and explain rationale when it’s not appropriate to meet the request

Design for the future including new user types & interfaces

Careful with “Other”

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For further reading: Bakken S et al. Toward Vocabulary Domain

Specifications for Health Level 7-coded Data Elements. JAMIA 7:333-342, 2000.

Cimino JJ. Desiderata for controlled medical vocabularies in the twenty-first century. Methods Inf Med. 1998 Nov;37(4-5):394-403

Chute CG. Cohn SP. Campbell JR. A framework for comprehensive health terminology systems in the United States. JAMIA 5(6):503-10, 1998 Nov-Dec.

ISO 1087-1:2000. Terminology Work-Vocabulary-Part 1: Theory and Application