Unmeasured confounding
“I congratulate the TIGER investigators for an interesting study that looked at a novel stentriever with adjustable radial size and force,” said Adam de Havenon, MD, assistant professor of neurology at the University of Utah, Salt Lake City, who was asked to comment on the study. “This intuitive concept shows promise in comparison to historical controls, and I look forward to hearing more about this exciting technology.”
The major advantage of the use of a composite historical control in the study is that fewer patients are needed for a trial, said Dr. de Havenon. This design makes the trial more economical and enables it to be completed more quickly.
“The impact is that a real-world patient could receive a beneficial treatment even sooner if it was shown to be beneficial with this study design,” he added. “The disadvantage is that there is unmeasured confounding because the historical controls come from trials during different time periods and at different centers and countries, with unique demographics that may not match well with your cohort.”
Statistical methodology helps mitigate this unmeasured confounding, but it remains a concern in the quest for a high level of evidence, Dr. de Havenon added.
The data suggest that the Tigertriever is a viable alternative to other stent retrievers, but they do not support its preferential use. “If the goal is to have the Tigertriever be considered a viable treatment option for large-vessel occlusion stroke, then [the researchers] have accomplished that with this study, which provides the needed data for FDA approval of the device,” said Dr. de Havenon.
“However, these data introduce the possibility of superiority but do not definitely show that,” he concluded. “To do so, they would need a randomized trial with a comparator device or devices and, as a result, a larger sample size.”
The study was funded by Rapid Medical. Dr. Gupta was one of the principal investigators for this study and for studies sponsored by Stryker Neurovascular, Zoll, and Vesalio. He served on the clinical events committee of a trial sponsored by Penumbra and has acted as a consultant for Cerenovous. Dr de Havenon disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.