Field-Based Stroke Severity Triage Significantly Improves Times to Endovascular Treatment for LVO

Mahesh Jayaraman, MD

Newly published findings in the Journal of Neurointerventional Surgery showed that the implementation of severity-based triage in emergency medical services (EMS) significantly reduced time to endovascular therapy (EVT) and improved overall outcomes for patients presenting with emergent large vessel occlusion (LVO). Considering the time-sensitive nature of stroke, these new data highlight the importance of how critical changing EMS protocols can be to patient survival.^1,2

The study compared times to treatment for 2 adjacent states, one with field triage and one without, being served by a single comprehensive stroke center (CSC). In State 1 (n = 407), scene to EVT time decreased 6%, or 8.13 minutes (P = .0004), every year, whereas no decrease was observed in State 2 (n = 232), which did not implement field triage (<1%; P = .94). Cumulatively over 5.5 years, there was a reduction of 43 minutes in time to EVT in State 1 vs no change in State 2.²

"The time lost in transfer from the nearest hospital to the best-equipped facility clearly jeopardizes a patient's chance of recovery,” lead investigator Mahesh Jayaraman, MD, neurointerventional radiologist and professor of diagnostic imaging, neurology, and neurosurgery, Brown University; and director, Neurovascular Center, Rhode Island Hospital, said in a statement.¹ "We hope this research persuades state governments to take a close look at their stroke care protocols and implement changes to improve triage and transport."

READ MORE: Stroke Risk Elevated in Women With Endometriosis

For patients with LVO, the reasoning for using field stroke triage is that it may better serve these individuals by facilitating direct transfer to endovascular capable centers thus avoiding hazardous delays between primary and CSCs. In addition to reduced times to treatment, investigators observed lower rates of disability in State 1, both for the entire cohort (all odds ratio [OR], 1.22; 95% CI, 1.07-1.40; P = .0032) and for those independent at baseline (OR, 1.36; 95% CI, 1.15-1.59; P = .0003).²

Jayaraman previously published similar research in 2020 comparing treatment and outcomes between patients taken to the closest primary stroke center (PSC; n = 144) with those triaged in the field to a more distant CSC (n = 88). Over 2 years, the median additional transport time to the CSC was 7 minutes. Times from scene departure to alteplase (50 vs 62 minutes; P <.001) and arterial puncture (93 vs 152 minutes; P <.001) were faster in the direct group. Among patients who were independent before the stroke, the OR for less disability in the direct group was 1.47 (95% CI, 1.13-1.93; P = .003) and 2.06 (95% CI, 1.10-3.89; P = .01) for the matched pairs.³

The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scale has been previously constructed and assessed to identify LVO in the prehospital setting. It was based on the National Institutes of Health Stroke Scale (NIHSS) with higher predictive value for LVOs and tested In the Screening Technology and Outcomes Project in Stroke (STOPStroke) cohort, in which patients underwent computed tomographic angiography within the first 24 hours of stroke onset.

In one 2016 analysis, LVO was detected in 33% of the 727-patient cohort. Results showed that FAST-ED had comparable accuracy to predict LVO to the NIHSS and higher accuracy than Rapid Arterial Occlusion Evaluation (RACE) scale and Cincinnati Prehospital Stroke Severity (CPSS) scale (area under the receiver operating curve: FAST-ED = 0.81; NIHSS = 0.80, P = .28; RACE = 0.77; P = .02; CPSS = 0.75; P = .002). A FAST-ED of at least 4 had sensitivity of 0.60, specificity of 0.89, positive predictive value of 0.72, and negative predictive value of 0.82 versus RACE scores of at least 5 of 0.55, 0.87, 0.68, and 0.79, and CPSS scores at least 2 of 0.56, 0.85, 0.65, and 0.78, respectively.⁴

REFERENCES
1. New study shows triaging stroke patients directly to level 1 (Comprehensive) stroke centers reduces time to treatment and improves patient outcomes. News release. Society of Neurointerventional Surgery. July 27, 2022. Accessed July 27, 2022. https://www.prnewswire.com/news-releases/new-study-shows-triaging-stroke-patients-directly-to-level-1-comprehensive-stroke-centers-reduces-time-to-treatment-and-improves-patient-outcomes-301594212.html
2. Jayaraman M, Baird G, Ouediat K, et al. long-term effect of field triage on times to endovascular treatment for emergent large vessel occlusion. J Neurointerv Surg. Published online July 27, 2022. doi:10.1136/jnis-2022-019250.
3. Field triage for endovascular stroke therapy: a population-based comparison. J Neurointerv Surg. 2020;12:233-239.
4. Lima FO, Silva GS, Furle KL, et al. Field assessment stroke triage for emergency destination: a simple and accurate prehospital scale to detect large vessel occlusion strokes. Stroke. 2016;47:1997-2002. doi:10.1161/STROKEAHA.116.013301