This document describes a study that identified questionable relationship triples in the Unified Medical Language System (UMLS) Metathesaurus. The researchers developed an algorithm to automatically identify suspicious relationship triples that fall into four cases: 1) conflicting hierarchical relationships, 2) redundant hierarchical relationships, 3) mixed hierarchical/lateral relationships, and 4) multiple mutually exclusive lateral relationships. Statistics on the identified questionable relationships in the UMLS 2010AA release are presented, along with a discussion of relationship issues that may arise from the integration of source vocabularies.

1. 1
Questionable Relationship
Triples in the UMLS
Huanying Gu, Gai Elhanan, Michael Halper, Zhe He
Structural Analysis of Biomedical Ontologies Center (SABOC),
New Jersey Institute of Technology, Newark, NJ

2. 2
Outline
„ Background
{ Biomedical terminologies and the UMLS
{ Relationships in the UMLS
„ Identify suspicious relationship triples
„ Results
„ Discussion

3. 3
Biomedical Terminologies
„ What is biomedical terminology?
{ A collection of concepts with attributes and
relationships
{ Used to encode drugs, diseases, diagnoses,
findings, etc.
„ The importance of biomedical terminologies
{ Clinical practice, e.g. ICD10 use in diagnosis coding
and billing
{ Biomedical research
{ Healthcare applications: EHR and EMR

4. 4
The Unified Medical Language System
„ A system that integrates more than 150
terminologies to enable interoperability between
computerized systems in healthcare industry
„ Designed and developed by United States
National Library of Medicine

5. 5
Structure of the UMLS
„ Two-level structure of the UMLS
{ Metathesaurus (META):
„ More than 2 million concepts
„ Terms from sources are grouped into concepts
„ More than 50 million relationships
{ Semantic Network
„ 133 semantic types
„ Each concept in META is assigned to at least one
semantic type

6. 6
Relationship in the META
„ UMLS META relationship:
{ Derived from the source
{ Introduced during the integration
„ 11 different relationship types (RELs):
{ Hierarchical relationships
„ Parent (PAR) and child (CHD)
„ Broader (RB) and narrower (RN)
{ Lateral (non-hierarchical) relationships
„ e.g. SY (synonym)

7. 7
Problems of Relationship Triples
„ Relationship in META is the foundation of concept
definitions
„ Problems of relationship triples:
{ There exist multiple relationships between the
same pair of concepts, they may be
„ from the same source
„ from different sources
{ Multiple RELs between a pair of concepts may
indicate problems

8. 8
Suspicious Relationship Triples
„ Relationship triple
{ Source concept – A
{ Target concept – B
{ Relationship – r
{ (r, A, B)
B
r1 r2
A

9. 9
Identify Suspicious Relationship Triples
„ Our algorithm automatically identifies all
suspicious relationship triples.
„ They are in the following 4 cases
{ Conflicting hierarchical RELs
{ Redundant hierarchical RELs
{ Mixed hierarchical/lateral RELs
{ Multiple mutually exclusive lateral RELs

10. 10
Case 1: Conflicting Hierarchical RELs
„ Two or more hierarchical RELs existing
between two different concepts forming a
hierarchical cycle where one or more RELs are
incorrect.
„ PAR and CHD
„ PAR and RN
„ RB and CHD
„ RB and RN
B
A
PAR
(RB)
CHD
(RN)

11. 11
Example of Case 1
Dermatologic
disorder
PAR
UMLS_CODE
C0037274
Inverse_isa
Dermatitis UMLS_CODE
C0011603
Dermatologic
disorder
UMLS_CODE
C0037274
Dermatitis UMLS_CODE
C0011603
conflicting hierarchical relationships
CHD
isa
CHD
isa

12. 12
Case 2: Redundant Hierarchical RELs
„ A concept is PAR (CHD) and RB (RN) of
another given concept at the same time
{PAR and RB
{CHD and RN
B
A
CHD
(RB)
RN
(PAR)

13. Case 3: Mixed Hierarchical/lateral RELs
13
„ Two different concepts A and B with one
hierarchical relationship and one lateral
relationship which are mutually exclusive and
cannot occur in the same pair of concepts at the
same time.
B
A
PAR
(CHD, RB,
RN)
Lateral
REL

14. 14
Examples of Case 2 & 3
Right suprascapular vein
Structure of
suprascapular vein
Right external
jugular vein
PAR
inverse_isa
RB (Broader)
inverse_isa
PAR
has_tributray
RO (other semantic relation)
has_tributary
RB and PAR: redundant
hierarchical relationships
PAR and RO:
mutually exclusive relationships

15. 15
Case 4: Multiple Lateral RELs
„ Two different concepts A and B with two lateral
relationships which are mutually exclusive.
Mutual exclusivity can only be asserted by the
relationship attributes qualifying both RELs
B
A
Lateral
REL
Lateral
REL

16. 16
Example for Case 4
SLE glomerulonephritis
syndrome, WHO class V
Lupus Erythematosus,
Systemic
RO
associated_with
RL
mapped_from
SLE glomerulonephritis
syndrome, WHO class V
RO
associated_with
Lupus Erythematosus,
Systemic
UMLS_CODE
C0268758
UMLS_CODE
C0024141

17. 17
2/21/2012
Statistics
„ Our methodology was applied to the UMLS
2010AA release.

18. 18
Discussion
„ Certain of REL triples can be attributed to the
process of the source vocabulary integration.
„ Questionable relationship triples may be an
indicator of term ambiguity.
„ Algorithmic approaches that can easily detect and
classify such errors are important.

19. „ This work was partially supported by the National
Library of Medicine, NIH R01 grant
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Acknowledgement and References

20. Thank you