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The Supplemental Qualifiers (SUPP–) special purpose dataset model is used to represent nonstandard variables (NSVs) which cannot be represented in an existing domain variable or an addtional variable from using standard variables from the domain or the SDTM.

The Related Records (RELREC) special-purpose dataset is used to describe relationships between records for a subject and relationships between datasets. 

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Once confirmed, determine whether adding a variable from the SDTM will fit the need. If adding a variable from the SDTM meets the need, then a Supplemental Qualifier dataset will not be implemented. Supplemental Qualifier datasets will only be implemented for domains when data are not in scope for a variable defined in the SDTM.

The Related Records (RELREC) special-purpose dataset is used to describe relationships between records for a subject and relationships between datasets. RELREC will not be used to represent relationships already represented in Supplemental Qualifier (SUPP–) datasets for nonstandard variables or the Comments (CO) dataset for unstructured free-text.

Relationships represented in RELREC are collected relationships. The RELREC dataset should be used to represent either:

• Explicit relationships, (e.g., concomitant medications taken as a result of an adverse event); or
• Information of a nature that necessitates using multiple datasets and that may need to be examined together for analysis or proper interpretation.  

Subject records or datasets expressing a relationship are specified using the key variables STUDYID, RDOMAIN (the domain code of the record or dataset in the relationship) with IDVAR (the variable that identifies the related record(s)). Each record in the RELREC special-purpose dataset contains keys that identify a record (or group of records) and an identifier for the relationship which is stored in the RELID variable. The value of RELID is chosen by the applicant and it is recommended that applicants use a standard system or naming convention for RELID (e.g., all letters, all numbers, capitalized).

Relationships Between Records for a Subject

Relationships between records for a subject are specified using the key variables STUDYID, RDOMAIN, and USUBJID, along with IDVAR and IDVARVAL (the value of the identifying variable). IDVARVAL will contain the value of the variable described in IDVAR. Single records can be related by using a unique-record-identifier variable such as --SEQ in IDVAR. Groups of records can be related by using grouping variables such as --GRPID in IDVAR.  Using --GRPID can be a more efficient method of representing relationships in RELREC when relating a single or group of records in one dataset to a group of records in another dataset. Variable RELTYPE will not be used when relating records for a subject and is only used when representing relationships between datasets. The value of RELID will be identical for all related records within USUBJID.

Relationships Between Datasets

Relationships between datasets are represented using a single record for each related dataset that identifies the key(s) of the dataset that can be used to relate the respective records. Relationships between datasets are specified using the key variables STUDYID, RDOMAIN, and IDVAR only. The values of variables USUBJID and IDVARVAL will be null as relationships between specific subject records will not be identified. The variable RELTYPE will identify the type of relationship between the datasets (e.g., a one-to-one or parent-child relationship). The allowable values for RELYPE are ONE and MANY per CDISC Controlled Terminology. This information defines how a merge/join would be written, and what would be the result of the merge/join. The possible combinations are:

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The SDTM does not allow the addition of new variables. Therefore, the supplemental qualifiers special-purpose dataset model is used to capture nonstandard variables and their association to parent records in general-observation class (Events, Findings, Interventions) datasets and Demographics (DM). Supplemental qualifiers are submitted via a separate SUPP-- dataset for each domain containing sponsor-defined variables (see Section 8.3, Supplemental Qualifiers - SUPP-- Datasets).

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