Sex in crossover [R for BE/BA]

posted by Helmut Homepage – Vienna, Austria, 2018-02-28 12:27  – Posting: # 18481
Views: 4,809

Dear Detlew,

» again asked: Why do you want to randomize gender (sex)?

Ana Christina wanted. I tried to help.

» Usually we randomize factors we want control for.
» But you can't control for gender (sex) in crossover experiments as long as you have subject in your evaluation model.

Sure. I knew that ANVISA in the past (dunno the current state) wanted to see analyses separately for sex (i.e., split of the data set, not as a covariate). Ana Christina  [image]… If one uses suitable software (:-D) imbalanced sequences are not a problem. I understand that (especially with many sequences and small sample sizes) one wants to keep sequences balanced at the beginning in order not to end up in disaster due to dropouts.

» Moreover it is highly debatable that gender differences are observable in crossover designs where we deal with differences between Test and Reference, both with the same active API in it.
» If there are gender differences in response to the API they are supposedly present in both formulations and cancel out.
» If not you have a gender-by-treatment interaction, aka subject-by-treatment interaction. The times of such an term are gone long years before when the "individual bioequivalence" was disestablished.


PS: Even if not “politically correct” I prefer sex (biological state) over gender (the FDA’s definition: “A person’s self representation as male or female, or how that person is responded to by social institutions based on the individual’s gender presentation.”). The way you dress or act will not change the PK. ;-)

Helmut Schütz

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