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Updated: Mar 11, 2026
Optimized Management of Endovascular Treatment for Acute Ischemic Stroke
Published on: January 18, 2018
Power of an Adaptive Trial Design for Endovascular Stroke Studies: Simulations Using IMS (Interventional Management
Maarten G Lansberg1, Ninad S Bhat2, Sharon D Yeatts2
1From the Stanford Stroke Center, School of Medicine (M.G.L., N.S.B., G.W.A.), Department of Statistics (T.L.L., P.W.L.), Department of Biomedical Data Science, School of Medicine (T.L.L., P.W.L.), Stanford University, CA; Department of Public Health Sciences, Medical University of South Carolina, Charleston (S.D.Y., Y.Y.P.); and Department of Neurology, University of Cincinnati Medical Center, OH (J.P.B.). lansberg@stanford.edu.
Background And Purpose:
Adaptive trial designs that allow enrichment of the study population through subgroup selection can increase the chance of a positive trial when there is a differential treatment effect among patient subgroups. The goal of this study is to illustrate the potential benefit of adaptive subgroup selection in endovascular stroke studies.
Methods:
We simulated the performance of a trial design with adaptive subgroup selection and compared it with that of a traditional design. Outcome data were based on 90-day modified Rankin Scale scores, observed in IMS III (Interventional Management of Stroke III), among patients with a vessel occlusion on baseline computed tomographic angiography (n=382). Patients were categorized based on 2 methods: (1) according to location of the arterial occlusive lesion and onset-to-randomization time and (2) according to onset-to-randomization time alone. The power to demonstrate a treatment benefit was based on 10 000 trial simulations for each design.
Results:
The treatment effect was relatively homogeneous across categories when patients were categorized based on arterial occlusive lesion and time. Consequently, the adaptive design had similar power (47%) compared with the fixed trial design (45%). There was a differential treatment effect when patients were categorized based on time alone, resulting in greater power with the adaptive design (82%) than with the fixed design (57%).
Conclusions:
These simulations, based on real-world patient data, indicate that adaptive subgroup selection has merit in endovascular stroke trials as it substantially increases power when the treatment effect differs among subgroups in a predicted pattern.
