Patient Characteristics
The first patient was enrolled in May 1999, and accrual closed in December 2004 based on a recommendation of the independent data and safety monitoring committee because of concerns regarding the extremely low mortality rate. Even if the trial had accrued the targeted 1900 patients, it would have taken more than 20 years of follow-up to observe 500 deaths at the realized event rate. At the time of the decision to terminate the study there had been no formal analysis comparing the survival experience between the 2 groups; the decision was based solely on the observed mortality rate for pooled data from the 2 groups. The date of last follow-up for this analysis was March 4, 2010.