1. The “Common Ontology” between ICD 11 and SNOMED CT
medical plausibility vs. ontological soundness
Stefan Schulz Medical University of Graz

2. ICD-11 – SNOMED CT harmonization
Background:
ICD: Classification maintained by WHO, currently under revision  ICD-11
SNOMED CT: Ontology-based clinical terminology maintained by IHTSDO (International Health Terminology Standards Development Organisation)
Large content overlap between ICD and SNOMED CT disorder / findings hierarchy
Joint Advisory Group (WHO and IHTSDO), based on institutional agreement:
Synergistic and not antagonistic terminology development
Jointly develop a common ontological basis for both ICD-11 and SNOMED CT
Maximum of interoperability between ICD and SNOMED coded data
It is quite natural to avoid competition between the the two artefacts

3. ICD-11 Foundation ICD-11 Foundation Ontology ICD-11 Content Model
External links
Common SNOMED – ICD-11 Ontology
Subset of SNOMED CT
Content
Model
Contents
Model Schema
Linearization A
Linearization B
(un-nested)
External sources
External Sources
ICD-11 Foundation
value sets
Linearization set A
(nested)
ICD-11 Foundation Ontology
Linearization C
ICD-11 Content Model
Query Library
Common SNOMED – ICD-11 Ontology
Subset of ICD-11

4. formal description of domain entities: clinical situations,
Categorization and
formal description of domain entities: clinical situations,
information entities, taxonomies, partonomies
Inventory of clinicians‘ language:
words, terms, phrases
Purpose-specific reporting units:
billing,
health statistics

5. SNOMED CT ICD-11 SNOMED CT ICD-11 Ontology Vocabulary Classification
Categorization and
formal description of domain entities: clinical situations, information entities, taxonomies, partonomies
Inventory of clinicians‘ language:
words, terms, phrases
Ontology
Vocabulary
SNOMED CT
SNOMED CT ICD-11
Purpose-specific reporting units:
billing,
health statistics,
research,…
Classification
ICD-11

6. SNOMED CT ICD-11 SNOMED CT ICD-11 Ontology Vocabulary Classification
Categorization and
formal description of domain entities: clinical situations, information entities, taxonomies, partonomies
Inventory of clinicians‘ language:
words, terms, phrases
Ontology
Vocabulary
SNOMED CT
SNOMED CT ICD-11
Purpose-specific reporting units:
billing,
health statistics,
research,…
Desiderata: context-independent, precise categorizations
Classification
Desiderata: Ready-to-use terms, one-click encoding of complex statements
ICD-11
Desiderata: pragmatic orderings for specific purposes

7. SNOMED CT Findings/Disorders and WHO – IHTSDO Common Ontology
Fracture of Radius
Fracture of Ulna
Formal taxonomies of clinical situations (life periods in which one or more clinical conditions are present)
Fracture of radius and ulna
ICD-11 Linearizations
Fracture of forearm
Fracture of shaft of ulna
Hierarchical orderings of reporting units into disjoint “classes”
Fracture of shaft of radius
Fracture of shafts of both ulna and radius

8. SNOMED CT Findings/Disorders and WHO – IHTSDO Common Ontology
Multiple hierarchies:
Mitral valve disease
Rheumatic heart disease
Formal taxonomies of clinical situations (life periods in which one or more clinical conditions are present)
Rheumatic mitral valve stenosis
ICD-11 Linearizations
Single hierarchies + exclusions
Mitral valve disease
Rheumatic heart disease
Hierarchical orderings of reporting units into disjoint “classes”
Excl: Heart valve diseases
Rheumatic mitral valve stenosis

9. SNOMED CT Findings/Disorders and WHO – IHTSDO Common Ontology
Strict taxonomic relations
Fibrosis of the skin
Disorder of skin of lower limb
Formal taxonomies of clinical situations (life periods in which one or more clinical conditions are present)
Lipodermatosclerosis
ICD-11 Linearizations
Approximate taxonomies
Chronic peripheral venous insufficiency
Hierarchical orderings of reporting units into disjoint “classes”
Lipodermatosclerosis

10. SNOMED CT Findings/Disorders and WHO – IHTSDO Common Ontology
Separation Ontology/ Epistemology
Tuberculosis
Confirmed present
Formal taxonomies of clinical situations (life periods in which one or more clinical conditions are present)
Tuberculosis of
respiratory system
Fusion Ontology/ Epistemology
ICD-11 Linearizations
Tuberculosis of the respiratory system
Hierarchical orderings of reporting units into disjoint “classes”
Respiratory tuberculosis, confirmed
Respiratory tuberculosis, suspected

11. SNOMED CT Findings/Disorders and WHO – IHTSDO Common OntologyB A C
Formal taxonomies of clinical situations (life periods in which one or more clinical conditions are present)
Mapping as Querying
Query mechanism, e.g. X = select A minus select B
Y = select A and B Z = select A and (rel C) …
ICD-11 Linearizations
Hierarchical orderings of reporting units into disjoint “classes” Y X Z

12. ICD-11 Foundation ICD-11 Foundation Ontology ICD-11 Content Model
External links
Common SNOMED – ICD-11 Ontology
Subset of SNOMED CT
Content
Model
Contents
Model Schema
Linearization A
Linearization B
(un-nested)
External sources
External Sources
ICD-11 Foundation
value sets
Linearization set A
(nested)
ICD-11 Foundation Ontology
Linearization C
ICD-11 Content Model
Query Library
Common SNOMED – ICD-11 Ontology
Subset of ICD-11