CDISC CRT-DDS 1.0

The CDISC CRT-DDS standard defines the metadata structures in a machine-readable XML format. These metadata structures are used to describe the CRT data sets and variables for regulatory submissions. The XML schema that is used to define the metadata structures in an XML format is based on an extension to the CDISC Operational Data Model (ODM).

CDISC CRT-DDS, Final Version 1.0, February 10, 2005

(Source: CDISC Case Report Tabulation Data Definition Specification)

In 1999, the FDA standardized the submission of clinical and non-clinical data and metadata in a set of eSubmission guidelines to include metadata descriptions of the data sets and columns within a Data Definition Document (define.pdf). In 2003, the FDA published a set of guidance documents on receiving electronic product applications per the International Conference on Harmonisation (ICH) electronic Common Technical Document (eCTD) specifications. In these specifications, the FDA expanded the acceptable file types to include the XML format.

The domain and column metadata that constitute the SAS representation of CDISC CRT-DDS 1.0 are derived from the global standards library in these formats:

As a general rule, the SAS representation of the CDISC CRT-DDS standard is patterned to match the XML element (data set) and attribute (column) structure of define.xml. For example, for CDISC SDTM, domain-level metadata is represented by a define.xml ItemGroupDef element. This metadata is captured in the ItemGroupDefs SAS data set. This is shown in the following code and table that represent the TE domain metadata:

<ItemGroupDef OID="docroot.IG.TE"
    Name="TE"
    Repeating="No"
    IsReferenceData="Yes"
    Purpose="Tabulation"
    def:Label="Trial Elements"
    def:Structure="One record per planned element"
    def:DomainKeys="STUDYID,ETCD"
    def:Class="Trial Design"
    def:ArchiveLocationID="ArchiveLocation.te">
    !-- All ItemRefs would be listed here -->
    <def:leaf ID="ArchiveLocation.te"
    xlink:href="te.xpt"> <def:title>te.xpt</def:title>
  </def:leaf>
</ItemGroupDef>

The following table lists the complete set of 39 tables that form the SAS Clinical Standards Toolkit SAS representation of the CDISC CRT-DDS 1.0 standard.

The highly structured nature of CDISC CRT-DDS data requires that any mapping to a relational format include a large number of data sets, with foreign key relationships to help preserve the intended non-relational object structure. In the SAS Clinical Standards Toolkit, foreign key relationships are enforced when validating the CDISC CRT-DDS data sets.

Field lengths in the CDISC CRT-DDS data sets are consistent by core data type. CDISC has not specified any limit to the length of most character fields. Arbitrary lengths have been chosen by data type. These lengths are listed in the following table. In the table, standard data types are distilled into core data types. To be safe, larger lengths have been chosen to ensure that no data loss occurs in the SAS Clinical Standards Toolkit pre-installed data sets. Production tables might be compressed using SAS mechanisms to preserve disk space.

The following table lists the data sets with member columns that form the CDISC CRT-DDS 1.0 data in the SAS Clinical Standards Toolkit.

No data set has more than one variable that acts as the key or index for that data set. The names of key variables are prepended with two asterisks (**). Some data sets do not have a key.

Foreign key variable names are prepended with two carat characters (^^). Foreign key variable names reference, in brackets [ ], the name of the data set for which it is a foreign key.

Required fields are marked with an X between brackets [X]. Required fields are fields for which a non-nil and non-whitespace-only value must be supplied in any observation for that data set.

Only the DefineDocument data set, which contains valid values for the FileOID and FileType variables, is needed to create a minimal, but valid CDISC CRT-DDS-compliant XML document. This is based on the CDISC CRT-DDS standard, which is very flexible.

All table and column names are case sensitive. They must be specified exactly as shown.

The SAS Clinical Standards Toolkit CDISC CRT-DDS reference standard supports reading and representing in SAS a define.xml file, building a define.xml file, and validating the structure and content of the SAS representation of a define.xml file. In addition, it validates the structural integrity of the define.xml file. To support this functionality, supplemental files include the following global standards library files:

It is this set of files, in whole or in part, that defines the CDISC CRT-DDS reference standard.