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Sample size re-estimation and other midcourse adjustments with sequential parallel comparison design
Rachel K Silverman1, Anastasia Ivanova1
1a Department of Biostatistics , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina , USA.
Abstract:
Sequential parallel comparison design (SPCD) was proposed to reduce placebo response in a randomized trial with placebo comparator. Subjects are randomized between placebo and drug in stage 1 of the trial, and then, placebo non-responders are re-randomized in stage 2. Efficacy analysis includes all data from stage 1 and all placebo non-responding subjects from stage 2. This article investigates the possibility to re-estimate the sample size and adjust the design parameters, allocation proportion to placebo in stage 1 of SPCD, and weight of stage 1 data in the overall efficacy test statistic during an interim analysis.
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