"Sex" and "gender" are similar but different concepts whose definitions and meanings can be confusing (see, for example, the article Sex and gender: What is the difference? from Medical News Today). The idea of sex as a binary concept where individuals are either male or female doesn't cover all people, and the meanings of "male" and "female" can also be unclear. So, how can information about sex and gender be represented in SDTM-based datasets?
The Demographics domain includes the variable SEX, with which the CDISC Controlled Terminology (CT) codelist named "Sex" is associated. The definitions of the terms in the codelist include:
|CDISC Submission Value
|A person who belongs to the sex that normally produces ova. The term is used to indicate biological sex distinctions, or cultural gender role distinctions, or both. (NCI)
|A person who belongs to the sex that normally produces sperm. The term is used to indicate biological sex distinctions, cultural gender role distinctions, or both. (NCI)
|A person (one of unisexual specimens) who is born with genitalia and/or secondary sexual characteristics of indeterminate sex, or which combine features of both sexes. (NCI)
Note that the definitions for Female and Male include the sentence: "The term is used to indicate biological sex distinctions, cultural gender role distinctions, or both." So this codelist doesn't help to characterize people who are undergoing or who have undergone sex change, or whose gender identity is different from their physical sex, and says nothing about sexual orientation. Since the SEX variable is required, implementers preparing a Demographics dataset have to do their best to choose a value from the Sex codelist to represent the data they collected, and, if necessary, can explain the process they used in the Clinical Study Data Reviewers Guide (cSDRG).
If data was collected about more specific aspects of sex or gender, that data can be represented in the Subject Characteristics (SC) domain. The CDISC codelists for Subject Characteristics Test Name and Test Code include the tests "Sex Reported at Birth" and "Gender Identity" and sponsors can add other tests they need. The team who developed the Therapeutic Area User Guide for HIV considered creating additional tests for inclusion in CDISC CT, but since terminology in this area is sensitive and currently fluid, the team did not define any additional tests or response terminology. Additional tests may be added to CDISC CT in the future, but would require careful definition and would have to be widely acceptable. In the meantime, implementers should document the test terminology they used for data collected about sex and gender represented in the SC domain.