A Short History of CDISC and SAS Transport Files

Background

When development of the SDTM and SDTMIG started, SAS was used almost universally across the pharmaceutical industry and at the US FDA.

"The SAS Version 5 (V5) transport file format is an open standard developed by SAS to support data transfers between systems, especially those running different operating systems."¹ SAS V5's designation as an open standard allowed FDA to specify it as the standard required for data submission.

The CDISC volunteer team that initially developed the SDTMIG was focusing on drug submissions to FDA, so it was assumed that SDTMIG had to work with the SAS V5 transport file format. This assumption led to the creation of rules such as a maximum variable name length of 8 characters, a maximum variable label length of 40 characters, and a maximum variable value length of 200 characters.

Current Regulation

At the time of updating this article, the FDA and the PMDA require SAS V5 transport file format and other regulatory agencies accept it.

If other recipients agree, SDTM-based data could be exchanged in another file format. If both parties agree, some of the restrictions rooted in the SAS V5 transport file format could be relaxed.

Responses to Changing Technology

Over the years, the CDISC user community has expanded; although SAS is widely used for statistical programming in that wider community, other languages (e.g., R) are also used and nontabular data formats (e.g., XML., RDF, newer SAS transport formats) are seeing greater use. In November 2012, the FDA held a public meeting during which these other alternatives were presented.

Subsequently, CDISC developed other formats that can be used to represent SDTM-based data: 

• Dataset-XML

• SDTM in RDF

• Dataset-JSON

Dataset-XML and SDTM in RDF were developed and tested in collaboration with the FDA. More recently, CDISC conducted 2 Dataset-JSON pilots, with the latest running from September 2023 through April 2024.^2,3

It is possible that in the future, regulatory agencies could require different file formats, or that other parties that exchange SDTM-based data could decide to require a different exchange format. If so, and if demand were great enough, CDISC could develop implementation advice for different exchange formats.

References

1. SAS Customer Support Center. New SAS® transport format and tools available. Accessed August 18, 2026. 

2. Anderson J, Hume S. Dataset-JSON pilot report and next steps. Paper presented at 2024 CDISC Japan Interchange. Accessed August 18, 2026. 

3. US Food and Drug Administration. Dataset-JSON pilot report and next steps. CDER Small Business and Industry presentation; July 25, 2024. Accessed August 18, 2026.