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Modeling data suggest how to increase access to endovascular therapy

 

Key clinical point: Several options are available to increase access to endovascular therapy for many Americans.

Major finding: Just 63% of Americans live within 60 minutes of a stroke center that provides endovascular therapy.

Data source: A geomapping study of the availability of endovascular therapy across the United States.

Disclosures: The study did not receive outside funding. Dr. Sarraj reported receiving a research grant from Stryker and serving as a consultant to or on the advisory board of the company.

Source: Sarraj A et al. ISC 2018 abstract 92.


 

REPORTING FROM ISC 2018

Only about two-thirds of the United States population has less than 60-minute access to a stroke center that is able to provide endovascular therapy, according to modeling of geomapping data.

The model showed that installing endovascular therapy (EVT) capability at 50 key hospitals could improve the proportion of Americans within 60 minutes of access to EVT from 63% to 71%, benefiting 22 million.

But another option could provide a stronger boost at a much lower cost. Emergency medical personnel could bypass nearby stroke centers that do not have EVT capability in favor of locations that do, even if they are a bit further away. That’s an option if the patient is clinically stable, and if they can successfully diagnose the patient with a large vessel occlusion, according to Amrou Sarraj, MD, director of the vascular neurology fellowship program at the University of Texas, Houston, who presented the study at the International Stroke Conference sponsored by the American Heart Association.

Paramedics wheel a patient into an ambulance. © Stockbyte/Thinkstock
Current stroke delivery protocols focus on delivering the patient to the nearest center that can administer intravenous tissue plasminogen therapy. For EVT, “it should be the same process,” Dr. Sarraj said.

In fact, taking patients to a hospital that does not conduct EVT can lead to delays. By the time the hospital admits the patient, determines that EVT therapy is appropriate, and transfers the patient to another facility, 3 hours can easily pass, he said. “That’s just an estimation from our experience. But if the other hospital is 15 miles away, that can be driven in a few minutes.”


To estimate time to access EVT centers, the researchers identified 1,645 U.S. stroke centers and stratified them into EVT (n = 577) or non-EVT (n = 1,068), based on whether they had reported at least one thrombectomy code for acute ischemic stroke in 2016 to the Centers for Medicare & Medicaid Services or if they had been designated as a comprehensive stroke center. The researchers broke down geographical units into areas with census tracts encompassing 2,500-8,000 people, and then calculated ground and air transportation times to EVT centers.

They used a ‘greedy’ algorithm to maximize the number of people with 60-minute access. This iterative approach yields the highest incremental increases in patient access and eliminates overlap. They conducted a similar optimization for 30-minute travel time.

The researchers found that 137 million Americans (44%) live within 30 minutes of an EVT center, 195 million (63%) live within 60 minutes, and 234 million (76%) within 90 minutes. By air, 172 million (56%) live within 30 minutes of an EVT center, 268 million (87%) within 60 minutes, and 296 million (96%) within 90 minutes.

“Flipping” the top 50 non-EVT centers to EVT centers would increase the number of Americans living within 60 minutes of an EVT center by 22 million, upping the percentage from 63% to 71%. The proportion within 30 minutes would increase by 15 million, from 44% to 49%.

In fact, the number of EVT-capable centers is rapidly expanding, having grown from 577 to 797 since 2016. But this is an expensive proposition, requiring the hiring of interventionists and other changes.

Another option is the “bypass” approach, in which emergency responders transport a patient with a large vessel occlusion to the nearest EVT-capable facility, if the distance isn’t too great. In Houston, the researchers calculated the impact of 15-, 30-, 45-, and 60-minute bypass limits. A total of 45% of the city’s population lives closest to a stroke center that performs EVT. If emergency responders were granted an additional 15 minutes to reach an EVT facility, 82% could go directly to a stroke center. That proportion rose to 91% for a 15- to 30-minute bypass, 94% for a 30- to 45-minute bypass, and 95% for a bypass up to 60 minutes.


In Texas overall, flipping the top five non-EVT centers would place an additional 1.8 million people (+7.0%) within 30 minutes of an EVT center, while a 30-minute bypass would add 11.3 million (+45%).

The study did not receive outside funding. Dr. Sarraj reported receiving a research grant from Stryker and serving as a consultant to or on the advisory board of the company.

SOURCE: Sarraj A et al. ISC 2018 abstract 92.

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