@Shedbuilder
Embarrassing, how do you construct a trial to take into account gender if as they say there is a huge spectrum of genders. I forget how many I've seen quoted: 700 or so was it?
I've not seen any trials that address 700 genders as that's a relatively recent development in trial design/funding terms - nor can I think of a clinical justification for investigating something with such poor/porous definitions.
The trials that I've seen would incorporate gender in sex workers (eg, the female-presenting males in some countries) as part of an investigation of the outreach work involved in promoting PrEp, say. That is, of course, relatively plain, old ordinary definitions of gender where they differ from biological sex.
There are observational studies and some longitudinal ones involving people who've had sex reassignment and they work off a similar view of gender.
There are observational studies that scrutinise sex and gender differences as they influence the expectation of social roles which can be problematic in the appropriate diagnosis of (say) autism. Similarly for substance use disorders. I've randomly selected this study as it identifies the need to understand sex and gender differences in this area:
pubmed.ncbi.nlm.nih.gov/29174306/
There have been some vaccine trials that also collected qualitative sex and gender data within the trial to investigate relevant differences and to explore if these resulted in different outcomes.