Since the FDA publicly presented clarification on the scope of SEND back in October 2020, the topic has been continually discussed and queried. The Technical Conformance Guide (TCG) was updated in September 2021 to give yet more detail and address specific areas that continue to cause confusion.  It seems to me that prior to that point, there had been quite widespread misunderstanding around areas such as the GLP status of a study and whether that impacted the agency’s requirement for SEND datasets.

I think that the TCG update is extremely helpful in clarifying many areas of confusion. It clearly states that studies require SEND datasets, regardless of study report status, GLP status, the drug substance or the age of the subject. On that  last point, it means that many juvenile studies are in-scope. It also clearly states that carcinogenicity studies are in scope as well as combined study types.

Aside from the requirement regarding the study start date, the document is essentially saying that the only studies out of scope of the SEND requirement, are those that are not modelled in the current SEND Implementation Guide (IG). I’ve often paraphrased this to simply state “If the study can be represented in SEND, then it should be represented in SEND”.

I believe it is widely acknowledged, that for many organizations this is quite, well, unpalatable. Our industry is now at a point where SEND feels just about manageable for most of the typical studies. Having to generate SEND datasets for less-typical studies becomes problematic. These studies will and do require greater levels of SEND expertise and individual attention. Obviously, specialist SEND vendors exist that can assist in these situations.

At this point it’s worth considering the question “Which studies can in fact be represented in SEND?”. It may seem like a straightforward question; however, the answer is open to debate. Not every endpoint will have an example in the Implementation Guide, so looking at the Controlled Terminology (CT) gives us long lists of tests that can be included in SEND datasets, yet these CT lists are extensible, meaning that if a study includes a test not listed, it can still be included in SEND. For data which do not naturally fit in a published domain, SEND provides the facility to have custom domains, and of course we can include additional detail through non-standard variables.

Therefore, as we have such a flexible and customizable standard, answering this question becomes difficult, as almost any study can be represented in SEND depending upon the lengths the data provider is willing to go to in order to provide customized datasets.

So, despite being nearly two years since the agency first clarified the scope of the SEND requirement, we still see many organizations questioning it and seeking further clarification. While the TCG does provide specifics, the reality is that different data providers are able to interpret it differently depending upon their capability with SEND.

As usual, if you would like to share your thoughts on the subject or would like some help in clearing up any confusion, you can reach me at

‘till next time


Published by Marc Ellison

Self-confessed SEND nerd who loves geek-ing out about everything to do with SEND. Active CDISC volunteer and member of the CDISC SEND extended leadership team. Director of SEND solutions at Instem responsible for all our industry leading SEND products and services.