ABSTRACT
The additional two stopping points were added to provide for early stopping of the trial in the event that the survival with the use of dantrolene IV was much lower than anticipated. Both are above the point at which one would conclude that the survival rate is significantly lower than 0.50, and preclude reaching that conclusion. The choice of points was somewhat arbitrary. For the survival rate of 0.85 assumed for the purposes of planning the trial, the addition of these two points affects the power less than 0.001; the power remains greater than 0.95.
