Clinical trial probability of success
The item-response approach consistently demonstrated higher PoS than the
SoS approach for all trial durations (Figure 4, upper). For the
item-response approach, the PoS was identical whether the tremor items
were included or not. For the SoS approach, the PoS estimated based on
all items was marginally higher than the one estimated without tremor
items. To achieve a 60% PoS in a 2-year trial, the item-response method
would require 280 patients per arm and the SoS analysis would require
570 patients per arm. As expected, longer trials produced higher PoS,
regardless of the analytical approach.