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Patient Transfer Before Thrombectomy Worsens Stroke Outcomes

Patients sent directly to a hospital for thrombectomy appear to have better outcomes.


 

HOUSTON—The drip-and-ship technique may not be the most time-effective way to treat patients with acute ischemic stroke who are candidates for endovascular thrombectomy, according to research presented at the International Stroke Conference 2017.

Results from two separate real-world, observational studies showed that patients with acute ischemic stroke and large-vessel occlusions amenable to mechanical thrombectomy had significantly worse clinical outcomes when their management path included a stop at a primary stroke center, followed by transfer to a comprehensive stroke center that had the capacity to perform thrombectomy, compared with going straight to the thrombectomy site.

Michael T. Froehler, MD, PhD

“Interhospital transfer was associated with significant delays to treatment and a significantly lower chance of a good outcome,” compared with taking patients directly from the site of stroke onset to a comprehensive stroke center, said Michael T. Froehler, MD, PhD, Assistant Professor at the Stroke Center and Cerebrovascular Service of Vanderbilt University in Nashville.

The findings show that “the system of care has room for improvement. Patients with large-vessel occlusions clearly do better when we get them to mechanical thrombectomy as quickly as possible,” said Dr. Froehler. Thrombectomy “has a more powerful treatment effect than t-PA, and we need to adjust our standard of care to best deliver” thrombectomy, he said.

Eric Smith, MD

“We have made progress in reducing door-to-needle times for delivering t-PA. Now we need a similar focus on thrombectomy. The challenge is to link the hospitals that do thrombectomy with the primary stroke centers that do not do thrombectomy and implement transfer or bypass agreements so patients quickly get to the right hospital. That is part of the push to treat as many eligible stroke patients with thrombectomy as possible,” said Eric Smith, MD, Medical Director of the Cognitive Neurosciences Clinic at the University of Calgary in Alberta.

Researchers Observed Better Outcomes Among Direct Patients

Dr. Froehler and colleagues used data collected in the Systematic Evaluation of Patients Treated With Stroke Devices for Acute Ischemic Stroke (STRATIS) registry, which began in 2014 and includes data for 984 patients with acute ischemic stroke with large-vessel occlusions treated by mechanical thrombectomy at any of 55 US centers. The series included 445 (45%) patients first seen at a primary stroke center and then transferred to a comprehensive center, and 539 (55%) who went directly to a comprehensive stroke center (ie, direct patients). Prior to thrombectomy, 628 patients (64%) received t-PA, with roughly similar percentages in the transferred and direct patients.

The median time from symptom onset to revascularization was 202 minutes among the direct patients and 312 minutes among patients first seen at a primary stroke center and then transferred, a statistically significant difference. The average time difference per patient between the two subgroups was 100 minutes, said Dr. Froehler.

This difference in time to reperfusion led directly to significant differences in functional outcomes after 90 days, as measured on the modified Rankin Scale (mRS). The percentage of patients with an mRS score of 0 or 1 was 38% among patients first seen at primary stroke centers, and 47% in direct patients. Overall, there was a 47% relative increase in excellent outcomes among the direct patients, compared with the patients who had been transferred. The percentage of patients with an mRS score of 0 to 2, which identifies functional independence post stroke, was 52% among transferred patients, and 60% in direct patients, indicating a 38% relative improvement among direct patients.

Stroke Transport and Delays at Primary Stroke Centers

The second study of stroke transfer times and outcomes used data from 562 patients with acute ischemic stroke and large-vessel occlusions treated in the Providence Health & Services system in five western US states between 2012 and 2016. Nearly half of the patients required a transfer, and the other half went directly to a center that performs thrombectomy. The analysis used clinical outcomes scored on the mRS at the time of hospital discharge.

Results from analyses that adjusted for baseline differences among the patients showed that patients who underwent an acute transfer were five times more likely to die during their index hospitalization or be discharged with moderate or severe disability, compared with direct patients. Patients initially seen at a primary stroke center were more than three times more likely to have these adverse outcomes, compared with direct patients. Further analyses showed that transferred patients and individuals initially treated at a primary stroke center were also significantly more likely to be discharged to a hospice, inpatient rehabilitation facility, or a skilled nursing facility, compared with direct patients, said Jason W. Tarpley, MD, a vascular neurologist at Providence Health & Services in Santa Monica, California.

Jason W. Tarpley, MD

“The big delay at primary stroke centers is the door-in–door-out time,” said Ryan McTaggart, MD, an interventional neuroradiologist at Rhode Island Hospital in Providence. He helped organize a partnership with 14 primary stroke centers in Rhode Island that uses a streamlined imaging, treatment (with t-PA), and transfer protocol that reduced transfer times by dozens of minutes and achieved a median time from onset of symptoms to revascularization by thrombectomy of 184 minutes in patients first seen at a primary stroke center. This result is shorter than the 202-minute median time from stroke onset to revascularization in the direct patients in Dr. Froehler’s study.

The best way to improve outcomes for patients with large-vessel occlusion is not to bypass primary stroke centers, but to make the primary centers more time efficient, said Dr. McTaggart. “Door-in–door-out time is the key metric for primary stroke centers, and they must try to keep it to less than 45 minutes,” he said.

Stroke transport and treatment networks are undergoing refinement in Tennessee, said Dr. Froehler. Considerations in Tennessee include how emergency medical service (EMS) workers assess patients with suspected stroke, decisions by EMS on where to take patients, and how quality of care is measured at primary and comprehensive stroke centers.

The STRATIS registry is sponsored by Medtronic. Dr. Froehler is a consultant to Medtronic, Blockade, Stryker, and Control Medical. Dr. Smith, Dr. Tarpley, and Dr. McTaggart had no disclosures.

Mitchel L. Zoler

Suggested Reading

Sonig A, Lin N, Krishna C, et al. Impact of transfer status on hospitalization cost and discharge disposition for acute ischemic stroke across the US. J Neurosurg. 2016;124(5):1228-1237.

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