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Summary of stroke clot removal treatment skimps on harms, evidence

Prompt clot-grabbing treatment produces better stroke outcomes

Our Review Summary

CT scan of brain show Ischemic Stroke or Hemorrhagic StrokeThis news release describes a study — the DAWN trial — which found that ischemic stroke patients that meet specific criteria may benefit from stroke clot removal (a procedure called a thrombectomy) up to 24 hours after the onset of a stroke.

The release is strong on context and explaining the procedure but would have been more informative with a more thorough discussion of harms and use of actual patient data rather than relative risk numbers when describing benefits.

We also reviewed a related story on the DEFUSE 3 trial which looked at blood-clot removal within a 16-hour window. Like this news release, that article skimped on cost, harms and study details.


Why This Matters

Strokes were the fifth-leading cause of death in the United States in 2016, and ischemic strokes (when a clot blocks a blood vessel) are by far the most common type. Before this trial and the new recommendations, doctors would only perform a thrombectomy within 6 hours of the onset of a stroke. This meant that many stroke patients, including those who had a stroke while sleeping, came to the hospital outside the window of this treatment. The expanded treatment guidelines are very important because they offer many more stroke patients a chance at a recovery with no or minimal brain damage.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The cost of a thrombectomy procedure isn’t addressed. Even through the study is comparing the procedure within 6 hours vs. within 24 hours, it would help readers if they knew how much this procedure runs.

From a health policy standpoint, expanding the treatment window for more people would certainly cost more, but just what those costs might be is hard to extrapolate.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The news release describes benefits in terms of relative risk, not absolute risk numbers. Each one-hour delay of treatment, they wrote, reduces the chance of recovery with minimal damage by 11%. Furthermore, patients who had their clots removed were 35.5% more likely to have minimal disability in the future. This was helpful, but it would be more informative to tell us how many patients had clots removed and what their outcomes were.

It also should have been emphasized that not all stroke patients are eligible for the procedure after 6 hours; according to the updated recommendations from the American Heart Association (AHA) and the American Stroke Association (ASA), only patients with a blood clot in a specific area of the brain, who have clinical symptoms that are disproportionate to the size of the stroke, are eligible for treatment after 6 hours.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

The news release skimmed over the harms associated with the procedure. As discussed in a previous review, there are adverse effects attributable to this procedure, including the risk of tearing an artery which could cause bleeding in the brain.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The DAWN trial that found the beneficial results of clot removal within 24 hours was a rigorous randomized clinical trial, involving 206 patients (107 received the thrombectomy, the others did not) and adjusted statistics. However, none of this was mentioned in the news release, which simply called it an “international trial.” This leaves the reader with no real sense of the quality of the evidence, though it turns out that the quality is quite good.

Does the news release commit disease-mongering?


No disease mongering.

Does the news release identify funding sources & disclose conflicts of interest?


The news release mentions that the DAWN trial was funded by Stryker Neuroendovascular. What it did not mention is that Stryker is a company that produces medical devices, and their device for clot removal was the only one used in the trial. Presumably, the good results from this trial will lead to an uptick in their product sales. Indeed, the news release from Stryker contains a lot more information about the specific product compared to this news release.

While many journalists reading the release will understand who Stryker is and why this represents a conflict of interest, consumers reading a reposted version of the release may not have that context. For their benefit, it would be better to spell things out directly.

Does the news release compare the new approach with existing alternatives?


The news release does a good job of explaining the comparison of doing the procedure between 6 and 24 hours after a stroke and not doing it. Theoretically, they could have compared the procedure to clot-busting medication which is sometimes used in these settings, but that would have been a different study altogether.

Does the news release establish the availability of the treatment/test/product/procedure?

Not Satisfactory

Unfortunately, this news release did not mention that the results from the DAWN trial contributed to updated guidelines for treatment issued by the AHA and the ASA. While thrombectomy after a stroke is already practiced in many larger centers across the country, it is unclear whether this treatment — actually an expanded indication for an existing treatment — will now be offered in more hospitals as a result. The release should have addressed that issue as well as described where the procedure is currently offered.

Does the news release establish the true novelty of the approach?


The news release established that this study was one of the first to demonstrate that clot removal between 6 and 24 hours can still be beneficial. It did not mention, however, another trial that also found similar results. The DEFUSE 3 trial, published last week, found that thrombectomy can be beneficial between 6 and 16 hours after the onset of a stroke. Both of these trials together were used to influence the updated AHA/ASA guidelines.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?


No unjustifiable language was used; the language of the news release was appropriately cautious and reinforced multiple times that even small delays in treatment could contribute to more brain damage.

Total Score: 5 of 10 Satisfactory


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