Bear

"If the data was so robust, why would they not still announce a passed futility analysis at 50% of events as originally planned? They can always stop the trial early at a later point in time (hopefully for good reasons) since there are more period DSMB reviews throughout the trial. I recall there already was a plan to do a sample size estimate analysis at 175 events. So they could have done both: announce futility analysis at 50% of events and still terminate early for good reasons at a later point."

if I remember correctly the FA change to 50% to 75% was done I believe so the date would be more statictically significant not for a lack of efficacy.