Patients who survive severe strokes have less disability 90 days afterward if EMS crews take them directly to distant comprehensive stroke centers (CSCs) that offer endovascular therapy (EVT), rather than primary stroke centers (PSCs) that may be closer but don’t.
That’s the verdict of a new study, “Field Triage for Endovascular Stroke Therapy: a Population-Based Comparison,” published in the Journal of Neurointerventional Surgery. Led by principal investigators Mahesh Jayaraman, MD, and Ryan McTaggart, MD, of Brown University’s Department of Neurosurgery, the study found that “triage based on EMS field severity assessment to a more distant CSC rather than a closer PSC was associated with significantly shorter time to EVT, better clinical outcomes, and no delay to alteplase [a thrombolytic drug that breaks up blood clots]… Seven additional minutes of prehospital transport was associated with nearly an hour faster time to EVT and a 16%–26% absolute increase in functional independence.”
“This is a significant improvement in outcomes in exchange for seven additional minutes of prehospital transport,” says Jayaraman, also director of the neurovascular center at Rhode Island Hospital. “By having EMS crews drive to a CSC rather than a closer PSC, the likelihood of a good outcome goes up 16%–26%.”
A Fundamental Question
The study was designed to answer a fundamental question regarding stroke treatment: Is it better for EMS crews to take all patients to the nearest PSC or to take those patients triaged as possibly having severe strokes to CSCs that offer EVT?
“Historically in the United States, protocols suggested EMS providers should take patients to the closest hospital as opposed to the most appropriate one for stroke,” says Jayaraman. “Yet when it comes to trauma and suspected heart attack, EMS crews are allowed to bypass a closer hospital and drive to centers that can offer a higher level of care.
“It makes sense that stroke patients receive the same approach to care,” Jayaraman says. “This is why Rhode Island has changed its EMS protocols to use a severity-based field triage algorithm. But we wanted to compare the results of patients triaged in this paradigm, as opposed to those taken to the closest PSC, to see what the differences actually were.”
To compile data to answer that question, the study used a sample group of 232 patients drawn from a single region served by a single CSC over a two-year period. Within this single geographic region, a portion of EMS providers had implemented severity-based triage, but the remainder had not. Of the patients, 144 were taken to the closest PSC, while 88 went to the more distant CSC. The median extra driving time to reach the CSCs was seven minutes, although this varied on a case-by-case basis.
Those patients who were taken to CSCs were triaged by EMS as having field Los Angeles Motor Scale scores of 4 or more, were within 24 hours of their time last known well, and were within 30 minutes’ drive to a CSC.
“Since some of the patients in the transfer group were outside the 30-minute radius to a CSC, we developed a matched-pair model from the two groups according to the times to the CSC and the patients’ NIH Stroke Scale readings,” says Jayaraman. “We had 70 matched pairs in all to ensure the statistical analysis would be as representative as possible.”
Why CSCs Made the Difference
The reason CSCs provides better severe stroke care than PSCs is their ability to provide endovascular therapy. In contrast, stroke victims taken to PSCs could receive alteplase, a medication that can break up some blood clots, but would have to be transported to a CSC for EVT. Either way, the result of going to a PSC resulted in stroke victims waiting longer to receive EVT—and thus deteriorating further until it was administered.
“Put simply, the time spent driving to more distant CSCs was more than offset by the time delay to EVT for patients taken to PSCs,” says Jayaraman.
Reducing the time to EVT translated to better outcomes overall. According to the study, “Direct transport to the CSC was associated with less disability at 90 days for all patients, including those with pre-existing disability.” Of stroke patients who were taken to CSCs and received EVT directly, 62% reached functional independence by 90 days, compared to 46% in the other group.
“Our results align with models suggesting that where the CSC and PSC are in close proximity, direct transport to the CSC was likely to result in better outcomes,” the study added. “One previous clinical series specifically examining direct field triage to a more distant CSC in Denmark observed similar results, with increased independence at 90 days (62% vs 43%) and a 58-minute reduction in time to EVT with direct transport.”
Implications for EMS
Based on these results, EMS should work to develop stroke triage protocols that mimic those for trauma and suspected heart attack in weighing destinations. Rather than transporting all patients to the closest center, severity-based triage for stroke reduces treatment time and improves outcomes.
“While each geographic region is different with unique challenges, the bottom line is that for severe stroke patients, the closest stroke center might not be most appropriate,” says Jayaraman. “We should all work on getting the right patient to the right place the first time.”
James Careless is a freelance writer and frequent contributor to EMS World.