CDISC Standards

The Clinical Data Interchange Standards Consortium (CDISC) defines the data models and metadata standards used in clinical trial submissions.

CDISC Data Models

graph TB
    subgraph "CDISC Standards Hierarchy"
        CDASH[CDASH<br/>Data Collection] --> SDTM[SDTM<br/>Tabulation]
        SDTM --> ADaM[ADaM<br/>Analysis]
        ADaM --> TFL[Tables, Figures,<br/>Listings]
    end

    subgraph "Submission Package"
        SDTM --> XPT1[SDTM XPT Files]
        ADaM --> XPT2[ADaM XPT Files]
        XPT1 --> DEFINE[define.xml]
        XPT2 --> DEFINE
    end

SDTM (Study Data Tabulation Model)

SDTM is the standard for organizing clinical trial tabulation data. Each domain (dataset) represents a specific type of data:

Creating SDTM Datasets

#![allow(unused)]
fn main() {
use xportrs::{Column, ColumnData, Dataset, Format, Xpt};

// Demographics (DM) domain
let dm = Dataset::with_label("DM", "Demographics", vec![
    Column::new("STUDYID", ColumnData::String(vec![Some("ABC-123".into())]))
        .with_label("Study Identifier"),
    Column::new("USUBJID", ColumnData::String(vec![Some("ABC-123-001".into())]))
        .with_label("Unique Subject Identifier"),
    Column::new("AGE", ColumnData::F64(vec![Some(45.0)]))
        .with_label("Age"),
    Column::new("SEX", ColumnData::String(vec![Some("M".into())]))
        .with_label("Sex"),
    Column::new("RACE", ColumnData::String(vec![Some("WHITE".into())]))
        .with_label("Race"),
]) ?;
}

ADaM (Analysis Data Model)

ADaM is the standard for analysis datasets derived from SDTM:

Creating ADaM Datasets

#![allow(unused)]
fn main() {
// Subject-Level Analysis Dataset (ADSL)
let adsl = Dataset::with_label("ADSL", "Subject Level Analysis", vec![
    Column::new("STUDYID", ColumnData::String(vec![Some("ABC-123".into())]))
        .with_label("Study Identifier"),
    Column::new("USUBJID", ColumnData::String(vec![Some("ABC-123-001".into())]))
        .with_label("Unique Subject Identifier"),
    Column::new("TRT01P", ColumnData::String(vec![Some("DRUG A".into())]))
        .with_label("Planned Treatment for Period 01"),
    Column::new("TRT01A", ColumnData::String(vec![Some("DRUG A".into())]))
        .with_label("Actual Treatment for Period 01"),
    Column::new("SAFFL", ColumnData::String(vec![Some("Y".into())]))
        .with_label("Safety Population Flag"),
]) ?;
}

Variable Metadata

CDISC requires specific metadata for each variable:

Required Metadata

Example with Full Metadata

#![allow(unused)]
fn main() {
Column::new("AESTDTC", ColumnData::String(vec![Some("2024-01-15".into())]))
.with_label("Start Date/Time of Adverse Event")
.with_format(Format::character(19))
.with_length(19)
}

Controlled Terminology

CDISC defines controlled terminology for many variables:

[!WARNING] xportrs does not validate controlled terminology values. Use Pinnacle 21 or similar tools to verify that coded values match CDISC controlled terminology.

Common controlled terminology:

• AESEV: MILD, MODERATE, SEVERE
• SEX: M, F, U, UNDIFFERENTIATED
• RACE: WHITE, BLACK OR AFRICAN AMERICAN, ASIAN, etc.
• NY (Yes/No): Y, N

SDTM-IG Versions

xportrs supports the latest SDTM-IG metadata requirements:

[!NOTE] As of SDTM-IG 3.3, variable labels are **recommended ** but not required for conformance. However, xportrs still generates warnings for missing labels since they are important for data reviewers.

Define-XML Integration

The define.xml file provides metadata that complements XPT files:

graph LR
    subgraph "Submission Package"
        XPT[XPT Files] -->|" Data "| FDA[FDA Review]
        DEFINE[define.xml] -->|" Metadata "| FDA
        XPT -.->|" Must match "| DEFINE
    end

[!IMPORTANT] Variable labels in XPT files should match those in define.xml. Pinnacle 21 rule SD0063 checks for mismatches.

Resources

• CDISC Website
• SDTM Implementation Guide
• ADaM Implementation Guide
• CDISC Controlled Terminology