On the Estimation of the Sample Size for the ECASS Study

Abstract

Recently a stroke trial — called the ECASS study — was set up. It is a double-blind, randomized, parallel study designed to compare the effect of alteplase and placebo on patients with acute ischemic stroke. The primary outcome of the study is the patient’s status at month 3 assessed by the Barthel index [5]. This index is a measure of quality-of-life, assessing the ability of the patient to perform his daily activities. A Barthel index score of 0 corresponds to complete dependence of the patient on others. We additionally introduced a score of 0 in case of death of the patient. A score of 100 implies that the patient can perform all his daily activities without any assistance. The latter can, but does not necessarily, imply complete neurologic recovery of the patient. Several versions of the Barthel index exist [2, 3]. The original scale increases or decreases with steps of 5, 10 or 15. Our version is a modified Barthel index, but for convenience we still call it the Barthel index.