New endpoints needed?
The investigators used noninferiority margins of 12%. “This question about the noninferiority margins, that’s a very tricky and difficult one in randomized clinical trials,” said Dr. Fischer. The investigators defined their margin using the 2015 HERMES data because no trials had yet compared direct mechanical thrombectomy and bridging thrombolysis at the time.
The researchers are performing a pooled analysis of all the trials that compared bridging thrombolysis with direct mechanical thrombectomy. “We are therefore looking at several margins, and I think this is the way we should look at these noninferiority margins,” said Dr. Fischer. “There’s not a clear-cut level which you can define.”
Enrollment in the trial was well balanced with respect to gender, which is not always the case in stroke studies, said Kevin Sheth, MD, professor of neurology and neurosurgery at Yale School of Medicine, New Haven, Conn., who commented on the study for this news organization.
The findings indicate that the likelihood of there being a difference between groups on this question is low, said Dr. Sheth. Both groups had large-vessel occlusion, both received thrombectomy, and both achieved reperfusion. But the higher rate of successful reperfusion in the bridging cohort was not reflected in any of the clinical endpoints that the investigators examined.
Observing a difference in this context will require very large trials or different endpoints that are more responsive to the intervention, said Dr. Sheth. “This is going to be a challenge for not just this but for any neuroprotection trial in the future,” he said.
The study was supported by Medtronic. Dr. Fischer has served as a consultant for Medtronic, Stryker, and CSL Behring. Dr. Sheth has disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.