Deep shit [RSABE / ABEL]

posted by Mikalai  – Belarus, 2020-01-31 17:07 (1532 d 20:16 ago) – Posting: # 21121
Views: 19,252

Dear Helmut

❝ Duno what you mean. Are you considering the sample size of a 2×2×2 crossover? The sample size of the 2-period 4-sequence full replicate is ~½ though the number of treatments / biosamples (driving the study cost) are essentially the same.

CV (%) ABE.2x2x2 ABE.2x2x4 n.ABEL n.ABEL.Bonf n.ABEL.adj n.Molins

    20        20        10     18          24         18       22

    30        40        20     34          44         42       42

    40        66        34     30          38         32       36

    50        98        50     28          34         28       32

❝ Try the functions pa.ABE() and pa.scABE() of PowerTOST.

❝ The plots in the slide are all for ABEL. A comparison of ABE and the EMA’s (unadjusted) ABEL:


❝ At 30% sample sizes are 40 and 34, at 40% 68 and 30.

❝ Hhm, not sure what you mean.

I just would like to say that it has no sense to conduct ABEL/RABE trials if the CV is assumed around 30% because, in order to control TIE, we have to increase the sample size to around that of usual ABE trials. It violates GCP principles in this case and invalidates the ABEL/RABE approach (subjects are subjected to unnecessary risks in the ABEL/RABE trials). And it very complicates the matter. Basically, when should we consider an ABEL/RABE trial?

Best regards

It also seems that when we wish to control TIE the sample size will be around 50 (worst scenario + dropout rate) in almost every case (usually little known about reference withindividual variability) of the ABEL/RABE. But I have rarely seen such trials.


Edit: Merged with a later (now deleted) post. You can edit your posts for 24 hours. [Helmut]

Complete thread:

UA Flag
 Admin contact
22,980 posts in 4,821 threads, 1,659 registered users;
26 visitors (0 registered, 26 guests [including 10 identified bots]).
Forum time: 14:23 CEST (Europe/Vienna)

Never, never, never use any software!
Never, never, never trust any computer!    Detlew Labes

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz