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Module 6 · Part 2 · Data Architecture

Standardized Vocabularies

Learn the key medical terminologies and coding systems your registry should use to ensure data is interoperable, searchable, and ready for research.

Patient Registries 101 · Dr. Danielle Boyce · EpilepsyLive

Why standardized vocabularies matter

A diagnosis of "Duchenne muscular dystrophy" in your registry might be entered as "DMD", "Duchenne MD", "Duchenne muscular dystrophy", or "Duchenne's".
Standardized vocabularies solve this by assigning unique, stable codes to every concept.

ICD-10-CM (International Classification of Diseases, 10th Edition, Clinical Modification)

Use for: Diagnoses, symptoms, procedures.
Why it is important: EHRs store diagnoses as ICD-10 codes.
Limitation: ICD-10 is designed for billing, not research.
Resource: ICD-10-CM Browser

SNOMED CT (Systematized Nomenclature of Medicine, Clinical Terms)

Use for: Clinical findings, procedures, body structures, organisms, substances.
Why it is important: Used natively in EHR systems (Epic, Cerner) and required for FHIR interoperability.
Resource: SNOMED CT Browser

LOINC (Logical Observation Identifiers Names and Codes)

Use for: Laboratory tests, clinical measurements, patient-reported outcomes, survey questions.
Why it is important: Required for FHIR Observation resources.
Example: Serum creatinine = LOINC 2160-0.
Resource: LOINC Search

RxNorm

Use for: Medications.
Why it is important: Participants report medications in countless ways ("methotrexate", "MTX", "Rheumatrex", "25mg methotrexate weekly").
Resource: RxNorm Browser

Orphanet Rare Disease Ontology (ORDO)

Use for: Rare disease classification.
Why it is important: ICD-10 doesn't cover most rare diseases specifically.
Resource: Orphanet

MedDRA (Medical Dictionary for Regulatory Activities)

Use for: Adverse events, symptoms, medical history, primarily in a regulatory/clinical trial context.
Why it is important: Required for adverse event reporting to FDA and EMA.
Resource: MedDRA MSSO

Practical implementation

You don't need to implement every vocabulary at once.

Key resources

NLM Unified Medical Language System (UMLS) , Maps between vocabularies
OBO Foundry , Open biological ontologies
NCBO BioPortal , Browse and search biomedical ontologies
HL7 Terminology , FHIR-aligned value sets
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