You are viewing an old version of this page. View the current version.

Compare with Current View Page History

Version 1 Next »

Grouping variables are Identifiers and qualifiers that group records in the SDTM domains/datasets, such as the --CAT (category) and --SCAT (subcategory) variables assigned by sponsors to categorize data. For example, a lab record with LBTEST = "SODIUM" might have LBCAT = "CHEMISTRY" and LBSCAT = "ELECTROLYTES". Values for --CAT and --SCAT should not be redundant with the domain or dictionary classification provided by --DECOD and --BODSYS.

Hierarchy of Grouping Variables

  • STUDYID
    • DOMAIN
      • --CAT
        • --SCAT
          • USUBJID
            • --GRPID
              • --REFID

How Grouping Variables Group Data

  1. For the subject
    1. All records with the same USUBJID value are a group of records that describe that subject.
  2. Across subjects (records with different USUBJID values)
    1. All records with the same STUDYID value are a group of records that describe that study.
    2. All records with the same DOMAIN value are a group of records that describe that domain.
  3. --CAT and --SCAT values further subset groups of tests within a domain. Generally, --CAT/--SCAT values have meaning within a particular domain, and apply to all subjects within that domain.
    1. --GRPID values further group (subset) records within USUBJID. Unlike --CAT and --SCAT, --GRPID values are not intended to have any meaning across subjects and they are usually assigned during or after data collection.
    2. Although --SPID and --REFID are identifier variables, these are usually not considered to be grouping variables, although they may have meaning across domains.

Differences Between Grouping Variables

  1. The primary distinctions between -CAT/ SCAT and --GRPID are:
    1. --CAT/ SCAT are known (identified) about the data before it is collected. --CAT/ SCAT values group data across subjects. --CAT/-SCAT may have some controlled terminology.
    2. --GRPID is usually assigned during or after data collection at the discretion of the sponsor. --GRPID groups data only within a subject. --GRPID values are sponsor-defined and are not be subject to controlled terminology.
  2. The primary distinction between -CAT/ SCAT and --REFID is that --CAT/-SCAT are usually textual descriptions of the data designed into the collection vehicle/process, and --REFID is usually a tracking number/value of some type assigned to an object being tracked (e.g., a blood sample).

In domains based on the Findings general observation class, the --RESCAT variable can be used to categorize results after the fact. --CAT and --SCAT by contrast, are generally predefined or used at the point of collection, not after assessing the value of findings results. See Section 6.3.3.2, Examples for Clinical Observations (CL) Domain Model, Example 3.

  • No labels