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Table 1 Decision criteria at the interim analysis and final analysis in the proposed design scenarios

From: Design considerations and analysis planning of a phase 2a proof of concept study in rheumatoid arthritis in the presence of possible non-monotonicity

Decision Criteria

Interim Success

Interim Futility

Final Success

Final Futility

Pr(|RED90 –Ctrl| > 0)

>95%

<20%

  

Pr(|RED90 –Ctrl| > 0.95)

>70%

   

Pr(|Rdmax –Ctrl| > 0) > 0.95 and Pr(|RED90 –Ctrl| > 0) >95%

  

Yes

No

  1. Pr(|RED90 –Ctrl| > 0): The probability of dose response near ED90 dose level achieves a drug effect greater than the control or placebo
  2. Pr(|RED90 –Ctrl| > 0.95): The probability of dose response near ED90 dose level achieves a drug effect greater than the control or placebo and 0.95 is the clinical significant difference
  3. Pr(|Rdmax –Ctrl| > 0): The probability of any dose with maximal effect achieves a drug effect greater than the control or placebo
  4. Only final success and futility are accessed in fixed design
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BMC Medical Research Methodology

ISSN: 1471-2288

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