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RegisterSequential trial with B method of Potvin [Two-Stage / GS Designs]
posted by Helmut 
– Vienna, Austria, 2015-10-01 20:13 (3453 d 12:48 ago) – Posting: # 15515
Views: 11,638
Hi 2×John,
I assume you are talking about the interim analysis after stage 1.
That’s a stupid situation indeed. Following the scheme you could continue according to the results for Cmax, but would have to stop ’cause of AUC. Since for regulatory acceptance you have to show BE for both – and there is a chance for Cmax – well, cough, did I say before that this a stupid situation?
What you could try: Estimate the total sample size for Cmax, assume that the GMR of AUC stays the same in the pooled analysis, and calculate the CI with the higher degrees of freedom. Does the CI shrink enough? If no, think twice whether you should proceed.
Can you give us some numbers to play with? n1 (if unbalanced, nRT and nTR), GMRs, CVs.
❝ In a sequential clinical trial conducted like a B method of Potvin, we have Cmax and AUC both not bioequivalent. Cmax has a power <80% (71.5%), and AUC>80% (84.6%).
❝ AUC 0-30min calculated by protocol is bioequivalent.
❝ In the protocol it was not specified how to proceed in this situation.
I assume you are talking about the interim analysis after stage 1.
❝ Can we calculate a new n and pass to the second phase? Or we must stop the trial?
That’s a stupid situation indeed. Following the scheme you could continue according to the results for Cmax, but would have to stop ’cause of AUC. Since for regulatory acceptance you have to show BE for both – and there is a chance for Cmax – well, cough, did I say before that this a stupid situation?
What you could try: Estimate the total sample size for Cmax, assume that the GMR of AUC stays the same in the pooled analysis, and calculate the CI with the higher degrees of freedom. Does the CI shrink enough? If no, think twice whether you should proceed.
Can you give us some numbers to play with? n1 (if unbalanced, nRT and nTR), GMRs, CVs.
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Helmut Schütz
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Complete thread:
- Sequential trial with B method of Potvin john john 2015-10-01 17:44 [Two-Stage / GS Designs]
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- Sequential trial with B method of Potvin ElMaestro 2015-10-01 17:58
- Sequential trial with B method of PotvinHelmut 2015-10-01 18:13
- Sequential trial with B method of Potvin john john 2015-10-07 11:26
- Power to the people d_labes 2015-10-07 13:49
- Power to the people john john 2015-10-07 14:54
- Software? Ethics beyond statistics… Helmut 2015-10-07 16:06
- Subtraction of a df ElMaestro 2015-10-07 21:22
- df = df-1 d_labes 2015-10-08 08:10
- Subtraction of a df ElMaestro 2015-10-07 21:22
- Software? Ethics beyond statistics… Helmut 2015-10-07 16:06
- Power to the people john john 2015-10-07 14:54
- Potvin B: α 0.0294 in both stages Helmut 2015-10-08 15:27
- Potvin B: α 0.0294 in both stages john john 2015-10-23 12:04
- Power to the people d_labes 2015-10-07 13:49
- Sequential trial with B method of Potvin john john 2015-10-07 11:26
Ing. Helmut Schütz