Treatment of Middle East respiratory syndrome with a combination of lopinavir/ritonavir and interferon-β1b (MIRACLE trial): statistical analysis plan for a recursive two-stage group sequential randomized controlled trial

Table 2 Stopping boundaries in the MIRACLE trial

Boundary	Value	Decision
Efficacy sopping boundary (α₁)	0	No stopping for efficacy
Futility stopping boundary (β₁)	0.2	Stop the trial for futility if less than stage-wise P-value
Efficacy stopping boundary (α₂)	0.2250	Stop trial for efficacy at the second stage or recalculate based on conditional power at first interim analysis

α1 is the maximum probability threshold under which the trial will be terminated early for efficacy. β1 is the maximum probability threshold above which the trial will be terminated for futility. α2 is the maximum probability threshold (the sum of the stage-wise p-values), above which the study will be declared as met its endpoint

ISSN: 1745-6215