Key points are not available for this paper at this time.
A group sequential method is proposed for the periodic analysis of accumulating data in clinical trials which are essentially one-sided as in treatment-placebo studies. The proposed boundaries retain the early stopping properties of the procedure described previously by DeMets & Ware (1980) when treatment appears to be ineffective or harmful but incorporate the more stringent requirements of the model proposed by O'Brien & Fleming (1979) for early rejection of the null hypothesis in favour of treatment.
DeMets et al. (Fri,) studied this question.