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A seemingly simple case is the editions of ICD, e.g. ICD9, ICD10, ICD11 - these are usually considered separate terminologies, since they are issued years apart and have significant differences. But we have also ICD9CM (US clinical modifications), ICD10AM ICD10-AM (Australian modifications) and many other variants. Can a code within ICD10AM ICD10-AM be considered to have the same meaning (classify the same real-world phenomena) as the same code in the original ICD10?
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SNOMED CT makes things even more complicated. It seems clear that SNOMED CT (20090101) and SNOMED CT (20090701) are two releases of the 'same' terminology, and that meanings don't change. But SNOMED CT also has the concept of 'modules', i.e. variants and extensions, such as 'the Australian extension', 'UK extension' and so on. The module concept can (apparently) be taken to any level of specificity, e.g. 'Australian pathology'. How are these extensions identified? For practical purposes we need to know if a term comes from the Australian extension or the international release. How do we identify the Australian extension? Is it 'SNOMED CT/-AU' or somesuch?
Terminology identification systems
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