We based the sample size for the trial on an assumed annual
primary-event rate of 1.98% in each group, a dropout
rate of less than 10.0%, a mean in-trial observation
time of 2.1 years, and a true hazard ratio
of 1.00. We determined that the enrollment of 3260 patients would be required to determine
the primary outcome in at least 122 patients and
provide a power of 90% to reject a hazard ratio
of at least 1.80 at the 0.05 level of significance.