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

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

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.

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.

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

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

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

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

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

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

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

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

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

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

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

ECO R European Centre for Ontological Research Generated post-coordinations SNOMED CT Concept original number number added% added ORGANISM PHYSICAL OBJECT SPECIAL CONCEPT CONTEXT-DEPENDENT CATEGORIES OBSERVABLE ENTITY PHYSICAL FORCE SOCIAL CONTEXT SPECIMEN EVENTS ENVIRONMENTS AND GEOGRAPHICAL LOCATIONS STAGING AND SCALES PROCEDURE BODY STRUCTURE PHARMACEUTICAL / BIOLOGIC PRODUCT FINDING ATTRIBUTE SUBSTANCE DISEASE QUALIFIER VALUE Total

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

ECO R European Centre for Ontological Research Reclassification example

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

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

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

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 ?