Simultaneous testing of noninferiority and superiority increases the false discovery rate

It is well recognized that multiplicity adjustment is not necessary in simultaneous testing for noninferiority and superiority. However, Ng (2003) argued that there will be more experimental treatments that are expected to have the same effect as the active control tested for superiority in simultaneous testing than would occur if only one null hypothesis is tested, thereby increasing erroneous claims of superiority. This leads to an increase in the false discovery rate for superiority.