1. ECO R European Centre for Ontological Research Ontology-based Error Detection in SNOMED-CT ® Werner Ceusters European Centre for Ontological Research Universität ds Saarlandes Barry Smith, Anand Kumar, Christoffel Dhaen

2. ECO R European Centre for Ontological Research Presentation overview Why this effort on SNOMED-CT ® ? Error detection algorithms Combining lexical and terminological relations Mistakes detected Automated post-coordination Mistakes detected Conclusion Future Work

3. ECO R European Centre for Ontological Research Snomed-CT ® in Europe ? 1 st Recommendation: Do conduct at least two major real life learning experiments with SNOMED. Make on the basis of the outcome a decision on SNOMED as a national standard.

4. ECO R European Centre for Ontological Research Description of Algorithms Ceusters W, Smith B, Kumar A, Dhaen C. Mistakes in Medical Ontologies: Where Do They Come From and How Can They Be Detected? in: Pisanelli DM (ed) IOS Press, Studies in Health Technology and Informatics, vol 102, 2004.

5. ECO R European Centre for Ontological Research Lexical, semantic and conceptual relations gall gallbladder urinary bladder urine urinary bladder inflammation gallbladder inflammation gall gall bladder bladder inflammation urine cystitis biliary cystitis gallbladder inflammation urinary bladder First algorithm

6. ECO R European Centre for Ontological Research Mistake indicator Conceptual search Term search

7. ECO R European Centre for Ontological Research Missed subsumption (1) Term search: heart tumor Concept search: heart structure AND tumor

8. ECO R European Centre for Ontological Research Missed subsumption (2) Missing: ISA neoplasm of heart

9. ECO R European Centre for Ontological Research Undetected synonymy (1) traumatic unilateral amputation of foot with complication unilateral traumatic amputation of foot with complication Traumatic amputation of foot isa open fracture head, femur Fracture of femur open fracture of head of femur Fracture of neck of femur isa

10. ECO R European Centre for Ontological Research Undetected synonymy (2) subcutaneous mastectomy for gynecomastia mastectomy for gynecomastia subcutaneous mastectomy isa

11. ECO R European Centre for Ontological Research Inadequate homonymy leg repair lower leg structure leg reconstruction lower limb structure Procedure-site

12. ECO R European Centre for Ontological Research Mistakes due to inappropriate lexical mapping structure of labial vein Vulval veinVein of head isa

13. ECO R European Centre for Ontological Research Total / partial inconsistencies terms

14. ECO R European Centre for Ontological Research Errors in direct (manual ?) subsumption assignment mediastinoscope diagnostic endoscopic examination of mediastinum NOS Inguinal hernia Lichtenstien repair of inguinal hernia isa

15. ECO R European Centre for Ontological Research Automated post-coordination using version space theory Guided creation of – Most specific generalisations: If there is a concept with properties P1 and P2, then create a concept that is defined by these properties – Most generic specialisations: Reclassify all existing concepts having the properties P1 and P2 Process guided by existing subsumption hierarchy Second algorithm

16. ECO R European Centre for Ontological Research Generated post-coordinations SNOMED CT Concept original number number added% added ORGANISM247682210.89 PHYSICAL OBJECT3336692.07 SPECIAL CONCEPT13000.00 CONTEXT-DEPENDENT CATEGORIES61722333.78 OBSERVABLE ENTITY6430330.51 PHYSICAL FORCE19931.51 SOCIAL CONTEXT51201913.73 SPECIMEN93614815.81 EVENTS7500.00 ENVIRONMENTS AND GEOGRAPHICAL LOCATIONS163150.31 STAGING AND SCALES111800.00 PROCEDURE5010743398.66 BODY STRUCTURE3073728179.16 PHARMACEUTICAL / BIOLOGIC PRODUCT136237515.51 FINDING3910523496.01 ATTRIBUTE97520.21 SUBSTANCE220625992.72 DISEASE7028656888.09 QUALIFIER VALUE79631031.29 Total 284773175516.16

17. ECO R European Centre for Ontological Research Suspicious configurations The presence of only one generated concept in a list of the concepts subsumed by a given concept; The presence of only one existing subsumed concept next to a list of generated concepts for the same subsumer; The presence of a pre- existing concept that is subsumed by a generated concept without any other additional relationships from the pre-existing concept to another one. (xxx) XXX (xxx) XXX

18. ECO R European Centre for Ontological Research Reclassification example

19. ECO R European Centre for Ontological Research Mereological errors (or peculiar meaning of “part of”) Structure of tibial nerve Thigh partLower leg structure isa

20. ECO R European Centre for Ontological Research Improper negation handling contracture of palmar fascia Dupuytren’s disease of palm, nodules with no contracture isa

21. ECO R European Centre for Ontological Research Conclusion SNOMED-CT ® is a great resource...... but must be improved: –... By removing inconsistencies at three levels: Lexical Semantic Conceptual –... Using adequate tools... to make it a better system –... for clinical code assignment –... for post hoc decision support on the basis of the codes

22. ECO R European Centre for Ontological Research Required future work Concept system ontology Concepts are unique units of thought. Disorders are concepts in which there is an explicit or implicit pathological process causing a state of disease which tends to exist for a significant length of time under ordinary circumstances. How ?