This section describes how the SDTM may be implemented to describe distinct relationships. Sets of variables used to represent relationships are detailed in the following sections. All relationships make use of the standard domain identifiers STUDYID, DOMAIN, and USUBJID.
When applicable, variables IDVAR and IDVARVAL represent variables and values which relate records by acting as record-level merge/join keys between datasets.
The following are examples of variables that could be used in IDVAR:
- Variables with values unique to each observation. When possible, variables with values from collected data are used (e.g., SPID, RECID), but variables with derived values may also be used (e.g., --SEQ).
- When relationship datasets (e.g., SUPPxx, FAxx, CO, RELREC) relate back to split parent domains, the value of IDVAR will be from a variable with unique values for each observation.
When possible, the variable represented in IDVAR will have values from collected data
- Variables from collected data
- The Sequence Number (--SEQ) variable uniquely identifies a record for a given USUBJID within a domain. The variable --SEQ is required in all domains except DM. For example, if a subject has 25 observations in the Vital Signs (VS) domain, then 25 unique VSSEQ values will be populated for the subject.
- The Reference Identifier (--REFID) variable can be used to capture an applicant-defined or external identifier, such as an identifier provided in an electronic data transfer.
- The Grouping Identifier (--GRPID) variable, used to link related records for a subject within a domain.
Overview
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