Obviously the choice of delta has a big impact on sample size required to provide robust evidence of efficacy. Let’s consider some examples. On the x-axis, we have assumed success rates FOR BOTH ARMS On the y-axis we have the sample size necessary to provide the burden of proof that a desired level of similarity is met with high confidence So when the underlying success rate if 80% for both AC and new -- we would need about 100 pts per arm with a delta of 15, 250 per arm for a delta of 10 and 1000 per arm for a delta of 10% Note that sample size requirements go down as the success rate approaches 100% and increase as the success rate approaches 50%.
Obviously the choice of delta has a big impact on sample size required to provide robust evidence of efficacy. Let’s consider some examples. On the x-axis, we have assumed success rates FOR BOTH ARMS On the y-axis we have the sample size necessary to provide the burden of proof that a desired level of similarity is met with high confidence So when the underlying success rate if 80% for both AC and new -- we would need about 100 pts per arm with a delta of 15, 250 per arm for a delta of 10 and 1000 per arm for a delta of 10% Note that sample size requirements go down as the success rate approaches 100% and increase as the success rate approaches 50%.
Transcript
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Issues in Selection of Deltas in Non-Inferiority Trials : Acute Bacterial Meningitis and Hospital-Acquired Pneumonia John H. Powers, M.D. Medical Officer Division of Special Pathogen and Immunologic Drug Products Center for Drug Evaluation and Research U.S. Food and Drug Administration
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