CDISC SDTM vs. ADaM: Core Differences & Architecture
The essential guide to tabulation standards (SDTM) vs. analysis-ready datasets (ADaM).
📌 Direct Answer / Executive Definition
CDISC SDTM (Study Data Tabulation Model) is a standardized format for storing raw clinical study data as collected on Case Report Forms (CRFs) with minimal transformation. CDISC ADaM (Analysis Data Model) is designed to be analysis-ready, containing derived variables, imputed dates, and population flags so that statistical procedures (PROC FREQ, PROC LIFETEST) can be run with zero extra data manipulation.
Why CDISC SDTM & ADaM Standards Matter for FDA Submissions
Both SDTM and ADaM are mandated by the US FDA, Japan PMDA, and European EMA for all electronic regulatory submissions under the eCTD framework.
Standard Syntax, Derivation & Framework Pattern
/* SDTM to ADaM Derivation: Transforming SDTM.DM + EX to ADaM.ADSL */
DATA work.adsl;
MERGE sdtm.dm(IN=in_dm) sdtm.ex(IN=in_ex);
BY USUBJID;
IF in_dm;
/* ADaM Standard Variable Derivations */
TRT01P = ARM; /* Planned Treatment */
TRT01A = ACTARM; /* Actual Treatment */
TRTSDT = INPUT(EXSTDTC, IS8601DA.); /* Treatment Start Date */
/* Deriving Subject Age in Years at Baseline */
IF BRTHDTC NE '' AND RFSTDTC NE '' THEN
AGE = FLOOR((INPUT(RFSTDTC, IS8601DA.) - INPUT(BRTHDTC, IS8601DA.)) / 365.25);
RUN;Core Rules & Certification Takeaways
- SDTM preserves raw observations grouped into domains (DM = Demographics, AE = Adverse Events, LB = Lab Data).
- ADaM is optimized for statistical analysis and consists of two primary models: ADSL (Subject-Level Analysis) and BDS (Basic Data Structure).
- Traceability is the golden rule: Every variable in an ADaM dataset must be clearly traceable back to its SDTM source in the define.xml metadata.
- Never run summary procedures directly on SDTM datasets for regulatory CSR tables; always build ADaM first.
🔗 Related Architectural Concepts & Next Steps
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Frequently Asked Questions (FAQ)
Can you generate CSR tables directly from SDTM datasets?
No. Regulatory agencies mandate that summary tables and statistical models be generated directly from validated ADaM datasets to ensure one-step traceability.
What is the primary subject identifier in CDISC standards?
USUBJID (Unique Subject Identifier), which globally identifies a subject across all domains, sites, and studies.
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