After about five years since the release of CDISC IG 3.4, CDISC has just released CDISC IG 4.0 and SDTM 3.0 for public review. Comments are due April 6, with expected final release expected later this year.
The public review includes the Conformance Rules version 3.0 as well as three draft Knowledge Base articles exploring some of the main changes expected with IG 4.0:
- NS– Datasets: Why they were built as they were.
- Why change the structure of SDTMIG metadata?
- Why does the DC domain differ from what’s described in FDA’s TCG?
For a quick overview of the impact of these changes, see the CDISC Standards timeline webpage or the revision history available in the draft version wiki for public review.
Celebrating or regretting the end of SUPP?
We will be moving, for example, from something called SUPPAE to something called NSAE, with a less “normalized” structure. Will this be “a small step for a man, a giant leap for mankind”? “Ai posteri l’ardua sentenza.”1
The change will require us to go from this:
to this:
The structure of these new dataset(s) is “One record per related dataset record,” meaning that the many-to-one relationship will no longer be possible, for example, an NS that applies to several records in the parent domain via –GRPID. That said, there is a hope that this new structure will simplify metadata handling and potentially facilitate the adoption of future data exchange format, such as CDISC Dataset-JSON.
Three new domains
Three new proposed domains have been introduced:
- DC (Demographics for Multiple Participations)
- GI (Gastrointestinal System Findings)
- EA (Event Adjudication) are three new proposed domains
DC has been around, unofficially, for some time, following the requirements introduced by the FDA in its FDA Study Technical Conformance Guide (see here my previous blog). This domain supports the representation of multiple enrollments within the same study. Along with DC, SUBJID has been added to all subject-level domains to differentiate data “generated” from each individual subjects’ participations.
Compared with FDA requirements, SDTM IG 4.0 also covers scenarios in which the same subject is enrolled multiple times, not only multiple screenings.
Identification of “Primary Enrollment,” and therefore how DM variables are populated, is left to the sponsor’s discretion. However, in cases where a subject experiences one or more screen failures before finally enrolling, the successful enrollment should clearly be considered the primary one.
EA, a Findings About domain, provides a common structure for studies requiring independent, peer-reviewed endpoint adjudication. In my view, it partially solves the issue of representing study endpoints where more complex “adjudication” is required; for example, in oncology study with efficacy based on tumor response.
Changes in metadata
Several new metadata have been introduced, along with some changes. The goal is to improve understanding of variables and their intended use, without impacting metadata included in a submission, e.g., define.xml.
So, when looking at the new SDTM IG, you will notice the following key differences among others:
- Controlled Terms, Codelist or Format is now split into three separate columns
- Variable Group has been added to group variables, for example Results Unit, or Results Value
- Some information previously included the “CDISC Notes” column are now reported in the “Examples” column
Other Changes
New versions of IGs are also an opportunity to fix issues (such as typos) and to clarify implementation that previously caused misunderstandings. For example, additional guidance on what Specimen-based Findings domain to use under specific circumstances, such as clarifying that anti-microbial antibody testing data should be mapped to IS domain rather than MS.
Some standard variables have been deprecated, such as –BLFL (Baseline Flag) for Findings domains, and others have been added. One notable addition is –CLASI variable, particularly useful for classifying Protocol Deviations to support requirements for “ICH E3 Q&As (R1)).” This variable is now officially part of the DV domain as DVCLASI, e.g., MINOR/MAJOR. More details on planned new and deprecated variables in all Observational Classes can be found in the CDISC Wiki.
Rumors about deprecating the PP domain appear to be unfounded, as PP is still there.
Want to know more?
You can participate in the public review and explore the details yourself. Check here.
My former colleague Varun Debbeti has also done an excellent job in his clinstandards webpage.
A more in-depth discussion of the expected changes will be also presented at upcoming CDISC-EU Interchange in May and this time in my hometown, Milan, and co-chaired by my colleague Silvia Faini.
Cytel will be present with two oral presentations and one poster:
- “It Got Worse Than Expected: Three Years of Retrospective CBER Requests on SDTM, ADaM, and TFLs” by Mark Malayas and Angelo Tinazzi
- “Authenticity Matters: Preserving Standards Integrity from Clinical Data Models to Tiramisù” by Angelo Tinazzi
- “JSON and CORE Unlocking Adoption” by Silvia Faini, Sebastià Barceló, Hugo Signol, and Angelo Tinazzi
See the here full draft agenda.
We look forward to reconnecting with colleagues from around the world, meeting new peers, and exchanging ideas at 2026 CDISC + TMF EU Interchange 2026.
See you in Milan?









