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For reasons such as reporting, analyses, common conventions, one can be motivated to represent a value content in multiple ways to serve their functional purposes. One must not, though, neglect to preserve each value's semantic meaning in the process of doing it. I will describe how we accomplish this goal in the SHARE MDR in this blog entry.

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:

Therefore, after annotating the above diagram with the AESEV example, we have:

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 the MDR are as follows:

  1. Proceed with building the remaining two permissible values
  2. Ensure each permissible value is part of the same concept
  3. Associate them to their respective codelists
  4. Assign the variables these codelists represent

The picture after stitching all these steps looks like this:

 

References

[1] Analysis Data Model (ADaM) Data Structure for Adverse Event Analysis. Section 4.1.8, pg 18. http://www.cdisc.org/system/files/members/standard/adam_ae_final_v1.pdf

[2] Value set for CDISC SDTM Severity Intensity Scale for Adverse Event Terminology. NCI Thesaurus. National Cancer Institute. http://ncit.nci.nih.gov/ncitbrowser/ajax?action=values&vsd_uri=http://evs.nci.nih.gov/valueset/C66769

[3] ISO/IEC11179-3 Information technology — Metadata registries (MDR) — Part 3: Registry metamodel and basic attributes. Third edition 2013-02-15. http://metadata-standards.org/11179/index.html

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