Deep shit [RSABE / ABEL]

posted by Mikalai  – Belarus, 2020-01-31 17:07 (1961 d 11:29 ago) – Posting: # 21121
Views: 26,615

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:

❝

❝ [image]

❝

❝ 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.

Regards

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

Complete thread:

UA Flag
Activity
 Admin contact
23,424 posts in 4,927 threads, 1,672 registered users;
14 visitors (0 registered, 14 guests [including 10 identified bots]).
Forum time: 05:36 CEST (Europe/Vienna)

To call the statistician after the experiment is done
may be no more than asking him to perform a postmortem examination:
he may be able to say what the experiment died of.    R.A. Fisher

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz
HTML5