Bioequivalence and Bioavailability Forum • Interim Analysis and Power

Interim Analysis and Power [Two-Stage / GS Designs]

posted by ElMaestro – Denmark, 2014-12-25 13:32 (4192 d 16:33 ago) – Posting: # 14173
Views: 8,846

Hi Emrah,

❝ I recently performed an interim analysis of a two-stage study with Potvin Method C and here are the initial results (power evaluated with alpha level of 0.05)

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❝ LN AUCT: 77.81 - 96.71 Power: 91.55%

❝ LN CMAX: 77.24 - 100.97 Power: 73.51

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❝ Given below the flowchart of Potvin method C, I believe this is a fail case where second stage is not required since power of only end-point is below 80%

❝

❝ Do you think is this the right way interpreting the results ?

I assume you wrote in your protocol that your way through the decision tree would be dictated by Cmax and not AUCt? You'll be going into stage 2 before declaring success or failure.

Please help me understand the details. I get on basis of Cmax:
PE=88.31% and CV=27.5% with N1=24, and assuming balance you'll have a power of about 65% (alpha 5%, GMR 95% as per Potvin and not 88.31%). Where did I go wrong here?

—
Pass or fail!
ElMaestro

Complete thread:

Interim Analysis and Power Emrah Soner Özdeş 2014-12-24 07:38
- Interim Analysis and Power Helmut 2014-12-24 16:22
  - Interim Analysis and Power Emrah Soner Özdeş 2014-12-25 08:36
- Interim Analysis and PowerElMaestro 2014-12-25 12:32
  - Interim Analysis and Power Emrah Soner Özdeş 2014-12-26 08:55
    - R-code & some thoughts Helmut 2014-12-26 17:51
      - R-code & some thoughts Emrah Soner Özdeş 2014-12-29 07:49