Optimizing Prehospital Triage for Patients With Stroke Involving Large Vessel Occlusion: The Road Less Traveled

Emergency medical service response for cases of stroke-suspected seizure: A population-based study

OBJECTIVES

We evaluated the on-scene time of emergency medical services (EMS) for cases where discrimination between acute stroke and epileptic seizures at the initial examination was difficult and identified factors linked to delays in such scenarios.

MATERIALS AND METHODS

A retrospective review of cases with suspected seizure using the EMS database of fire departments across six Japanese cities between 2016 and 2021 was conducted. Patient classification was based on transport codes. We defined cases with stroke-suspected seizure as those in whom epileptic seizure was difficult to differentiate from stroke and evaluated their EMS on-scene time compared to those with epileptic seizures.

RESULTS

Among 30,439 cases with any seizures, 292 cases of stroke-suspected seizure and 8,737 cases of epileptic seizure were included. EMS on-scene time in cases of stroke-suspected seizure was shorter than in those with epileptic seizure after propensity score matching (15.1±7.2 min vs. 17.0±9.0 min; p = 0.007). Factors associated with delays included transport during nighttime (odds ratio [OR], 1.73, 95 % confidence interval [CI] 1.02-2.93, p = 0.041) and transport during the 2020-2021 pandemic (OR, 1.77, 95 % CI 1.08-2.90, p = 0.022).

CONCLUSION

This study highlighted the difference between the characteristics in EMS for stroke and epileptic seizure by evaluating the response to cases with stroke-suspected seizure. Facilitating prompt and smooth transfers of such cases to an appropriate medical facility after admission could optimize the operation of specialized medical resources.

Reducing delay to endovascular reperfusion after relocating a thrombolysis unit

Background and aims

Functional outcome following mechanical thrombectomy (MT) in patients with acute ischemic stroke and large vessel occlusion is time-dependent and worsens with increasing delay. Time to endovascular reperfusion is potentially modifiable with changes in organizational structure. We investigated the changes in time to reperfusion of relocating the intravenous thrombolysis (IVT) services from a non-MT center to a MT-capable center.

Methods

We present an observational, consecutive, retrospective, single-center cohort study of 253 stroke patients treated with MT, 2017–2019. The observation period was divided into before and after the relocation of IVT services in 2018, period 1 and period 2, respectively. The two hospitals were located 13 km apart in an urban area, and following the relocation, IVT was administered at the MT-capable center. Time metrics were registered and divided into two main intervals, namely, ambulance departure from stroke onset location to imaging (ambulance-imaging) and imaging to reperfusion (imaging-reperfusion). The interval imaging-reperfusion included inter-hospital transfer to the MT-capable center in period 1. The association of the imaging-reperfusion duration and functional outcome at 90 days was analyzed using ordinal logistic regression.

Results

No significant change in ambulance-imaging was observed from a median of 27 min (interquartile range [IQR] 22–37) in period 1 to 30 min (IQR 23–40) in period 2, p = 0.19, while the median time of imaging-reperfusion decreased from 173 min (IQR 137–230) to 114 min (IQR 84–152), p < 0.001. The largest absolute time reduction from imaging to reperfusion was seen from imaging to arrival at the angio suite from 89 min (IQR 76–111) to 42 min (IQR 28–63), p < 0.001, which included inter-hospital transfer in period 1. In multivariate analysis, every 10 min of increased delay from imaging to reperfusion was associated with poorer functional outcome with an adjusted odds ratio of 0.95 (95% CI: 0.95–0.98), p < 0.001.

Conclusion

Relocation of IVT services to an MT-capable center was the main cause of reduced time to reperfusion for patients treated with MT and was implemented without affecting prehospital transportation time. These results suggest that patient outcome can be improved by optimizing the organization of IVT and MT services in urban areas.

Validation of field assessment stroke triage for emergency destination for prehospital use in a rural EMS system

BACKGROUND

Field Assessment Stroke Triage for Emergency Destination (FAST-ED) is a simple and accurate prehospital stroke severity scale that has been shown to have comparable accuracy to the gold standard National Institutes of Health Stroke Scale (NIHSS) but requires further field validation for use by emergency medical services (EMS), particularly in rural systems. FAST-ED scores ≥4 are considered high probability for large vessel occlusion (LVO) strokes, while scores <4 are low to moderate probability for LVO. The objective of this study was to assess inter-rater reliability of the EMS FAST-ED (EMS) score to the emergency department FAST-ED (ED-MD) scores.

METHODS

EMS calculated FAST-ED scores prior to transport to the emergency department (ED) on patients with a positive prehospital stroke screen. EDMD calculated FAST-ED scores for the same patients upon arrival to the ED. Interrater reliability and test characteristics were calculated.

RESULTS

A total of 95 patients were included in this study and 14 were subsequently diagnosed with an LVO. EMS assigned 34 patients (35.8%) a FAST-ED score of ≥4. EDMD assigned 25 patients (26.3%) a FAST-ED score of ≥4. Using the clinical cut-points of FAST-ED scores <4 and ≥ 4, a linearly weighted Cohen's kappa coefficient showed moderate interrater reliability when comparing EMS and EDMD scores (k_w 0.44, 95% CI 0.25-0.63). At ≥4, EMS FAST-ED scores had a sensitivity 0.48, specificity 0.75, PPV 0.62, NPV 0.62 for predicting an LVO, while EDMD FAST-ED scores had a sensitivity 0.36, specificity 0.82, PPV 0.64, NPV 0.60. Comparable receiver operator curve area under the curve values were obtained.

CONCLUSIONS

EMS and EDMD FAST-ED scores were moderately comparable in a rural EMS system. Similar NPVs compared to EDMD suggest the use of FAST-ED as an appropriate screening tool for EMS to predict the probability of LVO in the prehospital setting and make destination determinations regarding primary transport to a thrombectomy-capable stroke center.

Telestroke Consultation in the Emergency Medical Services Unit: A Novel Approach to Improve Thrombolysis Times

BACKGROUND

Faster treatment times are associated with improved outcomes in patients with acute ischemic stroke. In this prospective pilot study, we assess the feasibility of initiating telestroke consultation in emergency medical services unit (TEMS).

METHODS

Patients with stroke symptoms were evaluated via TEMS using a video-call with a stroke provider. After TEMS evaluation, patients were transferred to the nearest stroke center (NSC) or thrombectomy capable center (TCS) depending on stroke severity and symptom onset time. We compared time metrics between patients evaluated via TEMS to those via standard telestroke (STS) consultation.

RESULTS

49 patients were evaluated via TEMS between May 2017 and March 2020. Median age was 66, 24 (49%) were females, 15 (30.6%) received intravenous alteplase (tPA) after arrival to a local hospital, and 3 (6.1%) underwent mechanical thrombectomy (MT) after bypassing the NSC. Compared to 52 tPA patients treated through STS consultation, TEMS patients had shorter door to needle (DTN) time (21 vs. 38 min, p < 0.001). In addition, patients who received MT after bypassing the NSC had shorter onset to groin time compared to those transferred from NSC (216 vs. 293 min, P = 0.04).

CONCLUSION

Prehospital stroke triaging using TEMS is feasible, and could result in shorter DTN and onset to groin times.

Implementation of a Prehospital Stroke Triage System Using Symptom Severity and Teleconsultation in the Stockholm Stroke Triage Study

Importance

To our knowledge, it is unknown whether a prehospital stroke triage system combining symptom severity and teleconsultation could accurately select patients for primary stroke center bypass and hasten delivery of endovascular thrombectomy (EVT) without delaying intravenous thrombolysis (IVT).

Objective

To evaluate the predictive performance of the newly implemented Stockholm Stroke Triage System (SSTS) for large-artery occlusion (LAO) stroke and EVT initiation. Secondary objectives included evaluating whether the Stockholm Stroke Triage System shortened onset-to-puncture time for EVT and onset-to-needle time (ONT) for IVT.

Design, Setting, and Participants

This population-based prospective cohort study conducted from October 2017 to October 2018 across the Stockholm region (Sweden) included patients transported by first-priority ("code stroke") ambulance to the hospital for acute stroke suspected by an ambulance nurse and historical controls (October 2016-October 2017). Exclusion criteria were in-hospital stroke and helicopter or private transport. Of 2909 eligible patients, 4 (0.14%) declined participation.

Exposures

Patients were assessed by ambulance nurses with positive the face-arm-speech-time test or other stroke suspicion and were evaluated for moderate-to-severe hemiparesis (≥2 National Institutes of Health stroke scale points each on the ipsilateral arm and leg [A2L2 test]). If present, the comprehensive stroke center (CSC) stroke physician was teleconsulted by phone for confirmation of stroke suspicion, assessment of EVT eligibility, and direction to CSC or the nearest primary stroke center. If absent, the nearest hospital was prenotified.

Main Outcomes and Measures

Primary outcome: LAO stroke. Secondary outcomes: EVT initiation, onset-to-puncture time, and ONT. Predictive performance measures included sensitivity, specificity, positive and negative predictive values, the overall accuracy for LAO stroke, and EVT initiation.

Results

We recorded 2905 patients with code-stroke transports (1420 women [49%]), and of these, 323 (11%) had A2L2+ teleconsultation positive results and were triaged for direct transport to CSC (median age, 73 years [interquartile range (IQR), 64-82 years]; 55 women [48%]). Accuracy for LAO stroke was 87% (positive predictive value, 41%; negative predictive value, 93%) and 91% for EVT initiation (positive predictive value, 26%; negative predictive value, 99%). Endovascular thrombectomy was performed for 84 of 323 patients (26%) with triage-positive results and 35 of 2582 patients (1.4%) with triage-negative results. In EVT cases with a known onset time (77 [3%]), the median OPT was 137 minutes (IQR, 118-180; previous year, 206 minutes [IQR, 160-280]; n = 75) (P < .001). The regional median ONT (337 [12%]) was unchanged at 115 minutes (IQR, 83-164; previous year, 115 minutes [IQR, 85-161]; n = 360) (P = .79). The median CSC IVT door-to-needle time was 13 minutes (IQR, 10-18; 116 [4%]) (previous year, 31 minutes [IQR, 19-38]; n = 45) (P < .001).

Conclusions and Relevance

The Stockholm Stroke Triage System, which combines symptom severity and teleconsultation, results in markedly faster EVT delivery without delaying IVT.

Nationwide Analysis of Endovascular Thrombectomy Provider Specialization for Acute Stroke

Background and Purpose:

Determine the extent of cerebrovascular expertise among the specialties of proceduralists providing endovascular thrombectomy (ET) for emergent large vessel occlusion stroke in the modern era of acute stroke among Medicare beneficiaries

Methods:

Retrospective cohort study using validated International Classification of Diseases, Tenth Revision , Clinical Modification codes to identify admissions with acute ischemic stroke and treatment with ET. We identified proceduralist specialty by linking the National Provider Identifier provided by Medicare to the specialty listed in the National Provider Identifier database, grouping into radiology, neurology, neurosurgery, other surgical, and internal medicine. We calculated the number of proceduralists and hospitals who performed ET, ET team specialty composition by hospital, and number of proceduralists who performed ET at multiple hospitals.

Results:

Forty-two percent (n=5612) of ET were performed by radiology-background proceduralists, with unclear knowledge of how many were cerebrovascular specialists. Neurosurgery- and neurology-background interventionalists performed fewer but substantial numbers of cases, accounting for 24% (n=3217) and 23% (n=3124) of total cases, respectively. ET teams included a neurology- or neurosurgery-background proceduralist at 65% (n=407) of hospitals that performed ET and included both in 26% (n=160) of teams.

Conclusions:

Almost two-thirds of ET teams nationwide include a neurology- or neurosurgery-background proceduralist and higher volume centers in urban areas were more likely to have neurology- or neurosurgery-background proceduralists with cerebrovascular expertise on their team. It is unclear how many radiology-background interventionalists are cerebrovascular specialists versus generalists. Significant work remains to be done to understand the impact of proceduralist specialty, training, and cerebrovascular expertise on ET outcomes.

Bypassing the Closest Stroke Center for Thrombectomy Candidates

Background and Purpose—

Patients with acute ischemic stroke who have large vessel occlusion benefit from direct transport to a comprehensive stroke center (CSC) capable of endovascular therapy. To avoid harm for patients without large vessel occlusion from delayed access to intravenous thrombolysis (IVT), it has been suggested to only redirect patients with high likelihood of large vessel occlusion for whom the additional delay to intravenous thrombolysis (IVT) caused by transport to the CSC is below a certain threshold. However, which threshold achieves the greatest clinical benefit is unknown.

Methods—

We used mathematical modeling to calculate additional-delay-to-IVT thresholds associated with the greatest reduction in disability-adjusted life years in abstracted 2-stroke center and multiple-stroke center scenarios. Model parameters were extracted from recent meta-analyses or large prospective cohort studies. Uncertainty was quantified in probabilistic and 2-way univariate sensitivity analyses.

Results—

Assuming ideal treatment time performance metrics, transport to the nearest CSC was the preferred strategy irrespective of additional delay-to-IVT when the transfer time between primary stroke center and CSC was <40 minutes (95% credible interval: 25–66 minutes); otherwise, the optimal additional delay-to-IVT-threshold ranged from 28 to 139 minutes. In multiple-stroke center scenarios, optimal additional-delay-to-IVT thresholds were 30 to 54 minutes in urban and 49 to 141 minutes in rural settings; use of optimal thresholds as compared with a 15 minute-threshold saved 0 to 0.11 and 0 to 0.37 disability-adjusted life years per triage case, respectively. Assuming slower treatment times at primary stroke centers and CSCs yielded longer permissible additional delays.

Conclusions—

Our results suggest that patients with acute ischemic stroke with suspected large vessel occlusion should be redirected to a CSC if the additional delay to IVT is <30 minutes in urban and 50 minutes in rural settings.

Field triage for endovascular stroke therapy: a population-based comparison

Background

Endovascular therapy (EVT) for stroke improves outcomes but is time sensitive.

Objective

To compare times to treatment and outcomes between patients taken to the closest primary stroke center (PSC) with those triaged in the field to a more distant comprehensive stroke center (CSC).

Methods

During the study, a portion of our region allowed field triage of patients who met severity criteria to a more distant CSC than the closest PSC. The remaining patients were transported to the closest PSC. We compared times to treatment and clinical outcomes between those two groups. Additionally, we performed a matched-pairs analysis of patients from both groups on stroke severity and distance to CSC.

Results

Over 2 years, 232 patients met inclusion criteria and were closest from the field to a PSC; 144 were taken to the closest PSC and 88 to the more distant CSC. The median additional transport time to the CSC was 7 min. Times from scene departure to alteplase and arterial puncture were faster in the direct group (50 vs 62 min; 93 vs 152 min; p<0.001 for both). Among patients who were independent before the stroke, the OR for less disability in the direct group was 1.47 (95% CI 1.13 to 1.93, p=0.003), and 2.06 (95% CI 1.10 to 3.89, p=0.01) for the matched pairs.

Conclusions

In a densely populated setting, for patients with stroke who are EVT candidates and closest to a PSC from the field, triage to a slightly more distant CSC is associated with faster time to EVT, no delay to alteplase, and less disability at 90 days.

Comparative Evaluation of 10 Prehospital Triage Strategy Paradigms for Patients With Suspected Acute Ischemic Stroke

Background

The best strategy to identify patients with suspected acute ischemic stroke and unknown vessel status (large vessel occlusion) for direct transport to a comprehensive stroke center instead of a nearer primary stroke center is unknown.

Methods and Results

We used mathematical modeling to estimate the impact of 10 increasingly complex prehospital triage strategy paradigms on the reduction of population‐wide stroke‐related disability. The model was applied to suspected acute ischemic stroke patients in (1) abstract geographies, and (2) 3 real‐world urban and rural geographies in Germany. Transport times were estimated based on stroke center location and road infrastructure; spatial distribution of emergency medical services calls was derived from census data with high spatial granularity. Parameter uncertainty was quantified in sensitivity analyses. The mothership strategy was associated with a statistically significant population‐wide gain of 8 to 18 disability‐adjusted life years in the 3 real‐world geographies and in most simulated abstract geographies (net gain −4 to 66 disability‐adjusted life years). Of the more complex paradigms, transportation of patients with clinically suspected large vessel occlusion based on a dichotomous large vessel occlusion detection scale to the nearest comprehensive stroke center yielded an additional clinical benefit of up to 12 disability‐adjusted life years in some rural but not in urban geographies. Triage strategy paradigms based on probabilistic conditional modeling added an additional benefit of 0 to 4 disability‐adjusted life years over less complex strategies if based on variable cutoff scores.

Conclusions

Variable stroke severity cutoff scores were associated with the highest reduction in stroke‐related disability. The mothership strategy yielded better clinical outcome than the drip‐‘n'‐ship strategy in most geographies.

Real-World Treatment Trends in Endovascular Stroke Therapy

Background and Purpose- Recent landmark trials provided overwhelming evidence for effectiveness of endovascular stroke therapy (EST). Yet, the impact of these trials on clinical practice and effectiveness of EST among lower volume centers remains poorly characterized. Here, we determine population-level patterns in EST performance in US hospitals and compare EST outcomes from higher versus lower volume centers. Methods- Using validated diagnosis codes from data on all discharges from hospitals and Emergency Rooms in Florida (2006-2016) and the National Inpatient Sample (2012-2016) we identified patients with acute ischemic stroke treated with EST. The primary end point was good discharge outcome defined as discharge to home or acute rehabilitation facility. Multivariate regressions adjusted for medical comorbidities, intravenous tPA (tissue-type plasminogen activator) usage and annual hospital stroke volume were used to evaluate the likelihood of good outcome over time and by annual hospital EST volume. Results- A total of 3890 patients (median age, 73 [61-82] years, 51% female) with EST were identified in the Florida cohort and 42 505 (median age, 69 [58-79], 50% female) in the National Inpatient Sample. In both Florida and the National Inpatient Sample, the number of hospitals performing EST increased continuously. Increasing numbers of EST procedures were performed at lower annual EST volume hospitals over the studied time period. In adjusted multivariate regression, there was a continuous increase in the likelihood of good outcomes among patients treated in hospitals with increasing annual EST procedures per year (odds ratio, 1.1; 95% CI, 1.1-1.2 in Florida and odds ratio, 1.3; 95% CI, 1.2-1.4 in National Inpatient Sample). Conclusions- Analysis of population-level datasets of patients treated with EST from 2006 to 2016 demonstrated an increase in the number of centers performing EST, resulting in a greater number of procedures performed at lower volume centers. There was a positive association between EST volume and favorable discharge outcomes in EST-performing hospitals.