Proof-of-principle phase II MRI studies in stroke: Sample size estimates from dichotomous and continuous data

Abstract

BACKGROUND AND PURPOSE - Since the failure of a number of phase III trials of neuroprotection in ischemic stroke, the need for smaller phase II studies with MRI surrogates has emerged. There is, however, little information available about sample size requirements for such phase II trials and rarely enough patients in single studies to make robust estimates. We have formed an international collaborative group to assemble larger datasets and from these have generated sample size tables for MRI-based infarct expansion as the outcome measure. METHODS - Twelve centers from Australia, Europe, and North America contributed data from patients with hemispheric ischemic stroke. Infarct expansion was d..