Achieving interoperability in sharing and exchanging data between health information systems requires the support of standard medical terminology. To integrate standardised terminology into information systems, there is a need to map legacy interface terminology to a reference terminology. In this study, we mapped ICPC-2 PLUS, the interface terminology developed in Australia and classified to the International Classification of Primary Care Version 2, to the SNOMED CT terminology. We have developed a series of automated mapping algorithms to assist humans to perform the mapping. The Unified Medical Language System (UMLS) metathesaurus mapping, which utilises the links between ICPC-2 PLUS and SNOMED CT terms in the UMLS library mapped 46.5% of ICPC-2 PLUS terms to SNOMED CT. Lexical mapping explored the lexical similarities between terms in these two terminologies, and mapped 60.3% of ICPC-2 PLUS terms overall. Post-coordination of remaining unmapped terms was performed, allowing one ICPC-2 PLUS term to be mapped into composition with two SNOMED CT terms, which gives an increase of about 20% in mapped terms. Overall we have mapped 80.58% of ICPC-2 PLUS terms. A manual review of the mapping shows that about 90% of string-based mappings are accurate. Unmapped terms and mismatched terms are due to the differences in the structures between these two terminologies. Also, terms contained in ICPC-2 PLUS but not in SNOMED CT caused a large proportion of failures in the mappings.
Medical Terminology; Terminology Planning; ICPC-2 PLUS; SNOMED CT