Post hoc modification of non-inferiority margin
EVENT
One option is to simply select the non-inferiority margin at the analysis stage by looking at the SAFE frontier and selecting the non-inferiority margin corresponding to the observed control event risk. While this is a very straightforward and simple method, it is prone to inflation of type 1 error, as the same data are used twice: first, to select the non-inferiority margin and second, to test for non-inferiority using the same non-inferiority margin.More generally, it would represent a post hoc adjustment, unlikely to be acceptable to regulatory agencies.