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Let's start with an anatomy of metadata: A CDISC SDTM domain or ADaM dataset includes variables. A variable is either represented by a CDISC Controlled Terminology codelist or by a value format. For example, ADaM ADAE (adverse event analysis dataset) includes AESEV (Severity/Intensity) variable, which is represented by the AESEV (CDISC SDTM Severity Intensity Scale for Adverse Event Terminology) codelist.[1] This AESEV codelist has 3 permissible values, MILD, MODERATE, SEVERE, with specific meaning.[2]
This ISO 11179 metamodel region[3] can be used to generalize these metadata components:
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ADAE.AESEV has a numerical sibling, ADAE.AESEVN. Its CDISC Notes read "Code AE.AESEV to numeric," followed by "Low intensity should correspond to low value." Most important, its representation is "1, 2, 3". We can deduce using that information to say 1 corresponds to MILD, 2 to MODERATE, and 3 to SEVERE. In other words, 1 and MILD share the same value meaning, such that:
The remaining steps to do in the MDR are as follows:
The picture after stitching all these steps looks like this:
Notice, to the right on the picture, how the AESEV (C66769) codelist is associated to variables from 2 foundational standards? Therefore, at the physical layer, there are no ambiguations these variables in 2 datasets share the same semantic content, underscoring reusability.
In conclusion, ISO 11179 Part 3's concept region outlines a relationship that unifies concepts, terms, codelists, and semantics in a MDR. Though, in CDISC standards, it is rare to see multiple value domain sets having the same value meanings. This scenario is much more likely to exist in a pharma company. The ISO 3166 country code is a good example, which has multiple value domains. E.g., the long name for site management using a CTMS, the alpha-3 code for submission data specifically SDTM.DM.COUNTRY, etc.
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