SAS Representation of CDISC ADaM Metadata

The SAS Clinical Standards Toolkit provides a SAS metadata representation of each supported standard. The SAS Clinical Standards Toolkit implementation of the CDISC ADaM 2.1 standard provides an interpretation of Analysis Data Model, Version 2.1, ADaM document and the Analysis Data Model Implementation Guide, Version 1.0. The Analysis Data Model identifies four types of ADaM metadata that are captured and supported by the SAS Clinical Standards Toolkit.
The specific sources from the ADaM document for each metadata type are listed:
ADaM Document Sources for Each Metadata Type
Metadata Type
ADaM Document Source
Analysis Data Set
Section 5.1, Analysis Data Set Metadata, Table 5.1.1
Analysis Variable
Section 5.2, Analysis Variable Metadata, Table 5.2.1
Analysis Parameter
Section 5.2.1, Analysis Parameter Value-Level Metadata
Analysis Results
Section 5.3, Analysis Results Metadata, Table 5.3.1
In the SAS Clinical Standards Toolkit, the Analysis data set metadata is captured in the reference_tables and class_tables data sets, which are located here:
<global standards library directory>/standards/cdisc-adam-2.1-1.4/metadata
The SAS Clinical Standards Toolkit captures more metadata than might be specified for a standard. This helps support SAS Clinical Standards Toolkit functionality and provides greater consistency across supported standards.
This table provides the mapping of the Analysis data set metadata defined by the CDISC ADaM team to the SAS metadata representation in the reference_tables data set:
Analysis Data Set Metadata
Analysis Data Set Metadata Field**
Description**
reference_tables Column Mapping
DATASET NAME
The file name of the dataset, hyperlinked to the corresponding analysis dataset variable descriptions (i.e., the data definition table) within the define file.
table
DATASET DESCRIPTION
A short descriptive summary of the contents of the dataset
label
DATASET LOCATION
The folder and filename where the dataset can be found, ideally hyperlinked to the actual dataset (i.e., XPT file)
xmlpath
DATASET STRUCTURE
The level of detail represented by individual records in the dataset (e.g., “One record per subject,” “One record per subject per visit,” “One record per subject per event”).
structure
KEY VARIABLES OF DATASET
A list of variable names that parallels the structure, ideally uniquely identifies and indexes each record in the dataset.
keys
CLASS OF DATASET
Identification of the general class of the dataset using the name of the ADaM structure (i.e., “ADSL,” “BDS”) or “OTHER” if not an ADaM-specified structure
class
DOCUMENTATION
Description of the source data, processing steps, and analysis decisions pertaining to the creation of the dataset. Software code of various levels of functionality and complexity, such as pseudo-code or actual code fragments may be provided. Links or references to external documents (e.g., protocol, statistical analysis plan, software code) may be used.
documentation
**Source: Version 2.1 of the Analysis Data Model Document, Section 5.1, Analysis Dataset Metadata, Table 5.1.1
The reference_tables data set provided with the SAS Clinical Standards Toolkit 1.4 contains three records for the ADaM ADSL Analysis data set, a representative ADaM BDS data set, and an ADaM analysis results (RESULTS) data set. CDISC ADaM specifies that only the ADSL data set is required. Any number of BDS data sets can be defined as required for each study. A single, optional analysis results data set can be used for each study. Sample Reference_Tables Record (CDISC ADaM 2.1) lists the column contents for the ADSL data set record in the reference_tables data set.
In the SAS Clinical Standards Toolkit, Analysis Variable metadata is captured in the reference_columns and class_columns data sets in the global standards library folder:
<global standards library directory>/standards/cdisc-adam-2.1-1.4/metadata
This table provides the mapping of Analysis Variable metadata defined by the CDISC ADaM team to the SAS metadata representation in the reference_columns data set:
Analysis Variable Metadata
Analysis Variable Metadata Field**
Description**
reference_columns Column Mapping
DATASET NAME
The file name of the analysis dataset
table
VARIABLE NAME
The name of the variable
column
VARIABLE LABEL
A brief description of the variable
label
VARIABLE TYPE
The variable type. Valid values are as defined in the Case Report Tabulation Data Definition Specification Standard (e.g., in version 1.0.0 they include “text,” “integer,” and “float”)
xmldata type
DISPLAY FORMAT
The variable display information (i.e., the format used for the variable in a tabular or graphical presentation of results). It is suggested that the syntax be consistent with the format terminology incorporated in the software package used for analysis (e.g., $16 or 3.1 if using SAS).
displayformat
CODELIST / CONTROLLED TERMS
A list of valid values or allowable codes and their corresponding decodes for the variable. The field can include a reference to an external codelist (identified by name and version) or a hyperlink to a list of the values in the codelist/controlled terms section of the define file.
xmlcodelist
SOURCE / DERIVATION
Provides details about the variable’s lineage – what was the predecessor, where the variable came from in the source data (SDTM or other analysis dataset) or how the variable was derived. This field is used to identify the immediate predecessor source and/or a brief description of the algorithm or process applied to that sourceand can contain hyperlinked text that refers readers to additional information. The source / derivation can be as simple as a two level name (e.g., ADSL.AGEGR)identifying the data file and variable that is the source of the variable (i.e., a variable copied with no change). It can be a simple description of a derivation and the variable used in the derivation (e.g., “categorization of ADSL.BMI”). It can also be a complex algorithm, where the element contains a complete description of the derivation algorithm and/or a link to a document containing it and/or a link to the analysis dataset creation program.
sourcederivation
**Source: Analysis Data Model, Version 2.1, ADaM Document, Section 5.2, Analysis Variable Metadata, Table 5.2.1
The reference_columns data set provided with the SAS Clinical Standards Toolkit 1.4 contains one record for each column in each of the three data sets (ADSL, BDS, and RESULTS) in the reference_tables data set. This results in 63 records (columns) for ADSL, 142 records (columns) for BDS, and 13 records (columns) for the RESULTS data set.
Core reference_columns metadata for each column is in the Analysis Data Model Implementation Guide, Version 1.0. ADSL Columns as Specified in the Analysis Data Model Implementation Guide provides an excerpt of ADSL column metadata as itemized in Table 3.1.1 of the Analysis Data Model Implementation Guide, Version 1.0. This metadata has been translated into the SAS representation of ADSL as shown in ADSL Columns as Defined in reference_columns Data Set. (See also Sample Reference_Columns Record (CDISC ADaM 2.1), which provides the full set of column metadata for the BDS TRTP column in the reference_columns data set.)
ADSL Columns as Specified in the Analysis Data Model Implementation Guide
ADSL columns as specified in the ADaM Integration Guide
ADSL Columns as Defined in reference_columns Data Set
ADSL columns as defined in reference_columns data set
The SAS representation of ADaM analysis metadata in reference_tables and reference_columns provides a study template based on the Data Model Document and the Analysis Data Model Implementation Guide, Version 1.0. Each specific study implementation of ADaM creates multiple BDS data sets. The number of data sets is determined by the study design, the statistical analysis plan, and the available source data (for example, SDTM). Each analysis data set (including ADSL) might contain a different subset of columns defined by the CDISC ADaM model.
The SAS implementation makes assumptions about the data type and length of each column. These assumptions represent a typical implementation consistent with SDTM metadata and conventions for specific types of columns. For example, most identifiers have a default length of 40, most flags have a length of 1, and columns using controlled terminology are defined with a length that is long enough to capture the longest controlled term.
A third type of metadata identified in the Analysis Data Model, Version 2.1, ADaM Document (see ADaM Document Sources for Each Metadata Type) is analysis parameter value-level metadata. As noted in the ADaM document:
“Each BDS data set can contain multiple analysis parameters. In a BDS analysis dataset, the variable PARAM contains a unique description for every analysis parameter included in that dataset. Each value of PARAM identifies a set of one or more rows in the dataset. To describe how variable metadata vary by PARAM/PARAMCD, the metadata element PARAMETER IDENTIFIER is required in variable-level metadata for a BDS analysis dataset. This PARAMETER IDENTIFIER metadata element identifies which variables have metadata that vary depending on PARAM/PARAMCD, and links the metadata for a variable to the appropriate value of PARAM/PARAMCD.”
The reference_columns data set contains a column named parameterid that can be used to capture the value-level metadata for BDS data sets. For more information about analysis parameter value-level metadata, see sections 5.2.1 and 5.2.2 of the Analysis Data Model, Version 2.1, ADaM Document.
The final set of metadata prescribed by the Analysis Data Model, Version 2.1, ADaM Document is analysis results metadata. Analysis results metadata is described in the ADaM document:
“These metadata provide traceability from a result used in a statistical display to the data in the analysis data sets. Analysis results metadata are not required. Analysis results metadata describe the major attributes of a specified analysis result found in a clinical study report or submission.”
The metadata fields used to describe an analysis result are listed in Analysis Results Metadata. In the SAS Clinical Standards Toolkit, these metadata fields are captured in the reference_columns data set (where table=’RESULTS’), and serve as a template to initialize an analysis results data set. For more information, see ADaM Data Set Templates.
Analysis Results Metadata
Analysis Results Metadata Field**
Description**
reference_columns (value of column where table=’RESULTS’)
DISPLAY IDENTIFIER
A unique identifier for the specific analysis display (such as a table or figure number)
dispid
DISPLAY NAME
Title of display, including additional information if needed to describe and identify the display (e.g., analysis population)
dispname
RESULT IDENTIFIER
Identifies the specific analysis result within a display. For example, if there are multiple p-values on a display and the analysis results metadata specifically refers to one of them, this field identifies the p-value of interest. When combined with the display identifierprovides a unique identification of a specific analysis result.
resultid
PARAM
The analysis parameter in the BDS analysis dataset that is the focus of the analysis result. Does not apply if the result is not based on a BDS analysis dataset.
param
PARAMCD
Corresponds to PARAM in the BDS analysis dataset. Does not apply if the result is not based on a BDS analysis dataset.
paramcd
ANALYSIS VARIABLE
The analysis variable being analyzed
analvar
REASON
The rationale for performing this analysis. It indicates when the analysis was planned (e.g., “Pre-specified in Protocol,” “Pre-specified in SAP,” “Data Driven,” “Requested by Regulatory Agency”) and the purpose of the analysis within the body of evidence (e.g., “Primary Efficacy,” “Key Secondary Efficacy,” “Safety”). The terminology used is sponsor defined. An example of a reason is “Primary Efficacy Analysis as Pre-specified in Protocol.”
reason
DATASET
The name of the dataset used to generate the analysis result. In most cases, this is a single dataset. However, if multiple datasets are used, they are all listed here.
data sets
SELECTION CRITERIA
Specific and sufficient selection criteria for analysis subset and / or numerator– a complete list of the variables and their values used to identify the records selected for the analysis. Though the syntax is not ADaM-specified, the expectation is that the information could easily be included in a WHERE clause or something equivalent to ensureselecting the exact set of records appropriate for an analysis. This information is required if the analysis does not include every record in the analysis dataset.
selcrit
DOCUMENTATION
Textual description of the analysis performed. This information could be a text description, pseudo code, or a link to another document such as the protocol or statistical analysis plan, or a link to an analysis generation program (i.e., a statistical software program used to generate the analysis result). The contents of the documentation metadata element contains depends on the level of detail required to describe the analysis itself, whether or not the sponsor is providing a corresponding analysis generation program, and sponsor-specific requirements and standards. This documentation metadata element will remain free form, meaning it will not become subject to a rigid structure or controlled terminology.
document
PROGRAMMING STATEMENTS
The software programming code used to perform the specific analysis. This includes, for example, the model statement (using the specific variable names) and all technical specifications needed for reproducing the analysis (e.g., covariance structure). The name and version of the applicable software package should be specified either as part of this metadata element or in another document, such as a Reviewer’s Guide (see Appendix B for more information about a Reviewer’s Guide).
progstmt
**Source: Analysis Data Model, Version 2.1, ADaM Document, Section 5.3, Analysis Results Metadata, Table 5.3.1
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