Figure 2. Trends of EMA approvals with adaptive design trials from 2008 to 2020
Overall, adaptive designs were mainly composed of group sequential design (17/41, 41.46%) and seamless design (15/41, 36.59%). In the first period, the number of seamless designs was greater than that of group sequential design. From 2013 to 2016, the number of both designs was equal, but the proportion of group sequential design outweighed seamless design between 2017 and 2020. There was also an increase in the diversity of adaptive designs since 2017, which indicated that the planning of design modification had become much more flexible and adaptable (Figure 3).