Using SUPPQUAL for Specifying Natural Key Variables in Define.XML

Author: Sarath

Introduction

Define.XML plays a critical role in specifying dataset metadata, particularly in the context of clinical trial data. One important aspect of define.xml is the identification of natural keys, which ensure the uniqueness of records and define the sort order for datasets.

Using SUPPQUAL for Natural Keys

SUPPQUAL, or Supplemental Qualifiers, is a structure used in SDTM/SEND datasets to capture additional attributes related to study data that are not part of the standard domains. In certain cases, the standard SDTM/SEND variables may not be sufficient to fully describe the structure of collected study data. In these cases, SUPPQUAL variables can be utilized as part of the natural key to ensure complete and accurate dataset representation.

Example Scenarios

Consider a scenario where multiple records exist for a single subject in a dataset, with additional details captured in SUPPQUAL. If the standard variables (e.g., USUBJID, VISITNUM, --TESTCD) do not uniquely identify a record, SUPPQUAL variables such as QNAM or QVAL can be incorporated to achieve uniqueness.

Strategies for Incorporating SUPPQUAL Variables

When incorporating SUPPQUAL variables into the natural key, it is important to:

• Select SUPPQUAL variables that are consistently populated and relevant to the uniqueness of the records.
• Ensure that the selected SUPPQUAL variables contribute to the overall sort order and are aligned with the study's data structure.

Documenting SUPPQUAL Natural Keys in Define.XML

Documenting SUPPQUAL variables in define.xml requires careful attention to detail. Here is a step-by-step guide:

1. Identify the SUPPQUAL variables that need to be included in the natural key.
2. In the ItemGroupDef section of define.xml, ensure that these variables are listed as part of the Keys attribute.
3. Provide clear documentation in the ItemDef section, describing the role of each SUPPQUAL variable in the natural key.

Example XML snippet:

<ItemGroupDef OID="IG.SUPPQUAL" Name="SUPPQUAL" Repeating="Yes" IsReferenceData="No" Purpose="Tabulation">
    <!-- Define the key variables -->
    <ItemRef ItemOID="IT.USUBJID" OrderNumber="1" KeySequence="1"/>
    <ItemRef ItemOID="IT.RDOMAIN" OrderNumber="2" KeySequence="2"/>
    <ItemRef ItemOID="IT.IDVARVAL" OrderNumber="3" KeySequence="3"/>
    <ItemRef ItemOID="IT.QNAM" OrderNumber="4" KeySequence="4"/>
</ItemGroupDef>
    

Conclusion

Using SUPPQUAL variables as part of the natural key in define.xml can be a powerful strategy for ensuring accurate and comprehensive dataset documentation. By carefully selecting and documenting these variables, you can enhance the quality and integrity of your clinical trial data.

References

1. CDISC Define-XML Specification, Version 2.0. Available at: https://www.cdisc.org/standards/foundational/define-xml
2. CDISC SDTM Implementation Guide, Version 3.2. Available at: https://www.cdisc.org/standards/foundational/sdtm
3. FDA Study Data Technical Conformance Guide. Available at: https://www.fda.gov/media/130878/download
4. SAS Support - Define-XML 2.0: Generating XML Content with SAS. Available at: https://support.sas.com/resources/papers/proceedings15/3273-2015.pdf
5. How to use SUPPQUAL for specifying natural key variables in define.xml? Available at: https://www.lexjansen.com/phuse/2019/si/SI07.pdf