Cincinnati Prehospital Stroke Severity Research Articles

Validation of the prehospital stroke scales as a tool for in-hospital large vessel occlusion stroke: whether we satisfied?

Prehospital stroke severity scales have been widely used to identify whether community stroke patients presented with large vessel occlusion (LVO) or not. However, whether these scales are also applicable to in-hospital stroke patients remains unknown. We aim to validate and compare the predictive capability of these scales for these patients. From January 2016 to October 2020, a total of 243 patients who activated in-hospital stroke alerts, were included in this study. The area under the curve (AUC) was used to assess the predictive ability of five scales (Field Assessment Stroke Triage for Emergency Destination [FAST-ED], Rapid Arterial Occlusion Evaluation [RACE], Los Angeles Motor Scale [LAMS], Cincinnati Prehospital Stroke Severity Scale [CPSSS], and Prehospital Acute Stroke Severity scale [PASS]) for LVO. In addition, multivariable logistic analysis was adopted to determine the predictors of LVO in our patients cohort. Finally, 94 (38.7%) patients were confirmed presence of persistent LVO. The AUC for the FAST-ED, RACE, LAMS, CPSSS, and PASS scales to predict the presence of LVO in patients activating in-hospital stroke alerts were 0.82, 0.89, 0.86, 0.81, and 0.79, respectively. After multivariable analysis, baseline NIHSS (adjusted odds ratio [OR] = 1.160, 95% confidence interval [CI] = 1.110-1.212; P < 0.001) atrial fibrillation (adjusted OR = 2.940, 95% CI = 1.387-6.230; P = 0.005) and cardiac/pulmonary procedure (adjusted OR = 6.861, 95% CI = 2.437-19.315; P < 0.001) remained independent predictors of LVO. The prehospital stroke scales also showed good predictive capabilities in discriminating LVO among inpatients who activated stroke alerts. However, given that inpatients' history is more readily available, a specifically designed in-hospital stroke scale that combines stroke severity and history is warranted.

内因性脳梗塞が先行した外傷症例に対し急性期再灌流療法を施行した1例(A case of revascularization therapy for acute ischemic stroke with a chief complaint of traumatic injury)

要旨 標準的な外傷診療では生理学的機能の管理および安定化を重視しており，神経学的所見は見逃されやすい。内因性脳梗塞が先行した外傷症例の診療について検討した。症例は78歳の男性，階段2階の踊り場から転落した。右共同偏視，右片麻痺，Glasgow coma scale（GCS）12の意識障害を認めた。外傷全身computed tomography（CT）で頭蓋内に占拠性病変は認めず，動脈優位相で左中大脳動脈の造影欠損を認めた。急性期脳梗塞と診断し，機械的血栓回収療法を行った。外傷機転を介在する内因性脳梗塞では，見逃しや治療介入に時間を要する可能性がある。病院前脳卒中スケールが症状検出に役立つ可能性があり，頭頂部の動脈優位相を含む造影CT検査で主幹動脈閉塞の検索が可能である。画像評価には熟練を要するため，3次元画像処理を行うとともに，適切に専門医へコンサルトし早期診断治療へつなげることが重要である。

Validation of a shortened FAST-ED algorithm for smartphone app guided stroke triage

Background and Purpose:Large vessel occlusion (LVO) recognition scales were developed to identify patients with LVO-related acute ischemic stroke (AIS) on the scene of emergency. Thus, they may enable direct transport to a comprehensive stroke centre (CSC). In this study, we aim to validate a smartphone app-based stroke triage with a shortened form of the Field Assessment Stroke Triage for Emergency Destination (FAST-ED).Methods:This retrospective validation study included 2815 patients with confirmed acute stroke and suspected acute stroke but final diagnosis other than stroke (stroke mimics) who were admitted by emergency medical service (EMS) to the CSC of the Neurological University Hospital Essen, Germany. We analysed the predictive accuracy of a shortened digital app-based FAST-ED ( ‘FAST-ED App’) for LVO-related AIS and yield comparison to various other LVO recognition scales.Results:The shortened FAST-ED App had comparable test quality (Area under ROC = 0.887) to predict LVO-related AIS to the original FAST-ED (0.889) and RACE (0.883) and was superior to Cincinnati Prehospital Stroke Severity (CPSS), 3-Item Stroke Scale (3-ISS) and National Institute of Health Stroke Scale (NIHSS). A FAST-ED App ⩾ 4 revealed very good accuracy to detect LVO related AIS (sensitivity of 77% and a specificity 87%) with an area under the curve c-statistics of 0.89 (95% CI: 0.87–0.90). In a hypothetical triage model, the number needed to screen in order to avoid one secondary transportation in an urban setting would be five.Conclusion:This validation study of a shortened FAST-ED assessment for a smartphone-app guided stroke triage yields good quality to identify patients with LVO.

Reader response: Optimizing in-hospital triage for large vessel occlusion using a novel clinical scale (GAI2AA).

In their development of the GAI2AA scale,1 Ohta et al. identified a history of atrial fibrillation (AF) or AF on ECG as independent predictors of an anterior circulation large vessel occlusion (LVO) in patients presenting within 4.5 hours of symptom onset. Using a different case definition—all patients who had an occlusion of the common carotid, internal carotid, proximal middle cerebral, anterior or posterior cerebral arteries, or the vertebrobasilar system—and a different patient population—patients admitted to the University of Kentucky Medical Center vs 3 Japanese stroke centers—we also found that a history of AF was associated with an LVO (36.2% vs 18.5%, p < 0.001),2 although the frequency was less than reported by Ohta et al. (65% vs 24%, p < 0.001). In our cohort, the C-statistic for LVO based on a history of AF alone (0.579; 95% CI 0.540–0.617) reflected no more than moderate discriminative capacity and did not improve the accuracy of the Cincinnati Prehospital Stroke Severity scale, Los Angeles Motor Scale, Rapid Arterial Occlusion Evaluation score, or the Field Assessment Stroke Triage for Emergency Destination scale. Nonetheless, simply obtaining a history of AF can alert emergency responders that a patient with an acute focal neurologic deficit may have an LVO.

Effect of Known Atrial Fibrillation and Anticoagulation Status on the Prehospital Identification of Large Vessel Occlusion

Introduction: The Cincinnati Prehospital Stroke Severity scale (C-STAT), Los Angeles Motor Scale (LAMS), Rapid Arterial Occlusion Evaluation (RACE) score, and Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scales were designed to aid emergency responder identification of patients with stroke related to large vessel occlusion (LVO). We hypothesized that the addition of a known history of atrial fibrillation (AF) without anticoagulation to currently used scales would improve LVO detection. Methods: Medical records of patients admitted to a Comprehensive Stroke Center with acute ischemic stroke in 2014-2015 were reviewed. LVO identification using the C-STAT, LAMS, RACE, and FAST-ED scores and the AF variable were compared using univariable analyses. The areas under the receiver operating curves (AUCs) were then compared for each score, the AF variable, and each score with the addition of the AF variable. Results: The sample included 233 patients without and 188 patients with an LVO. A history of known AF, history of AF with no anticoagulation, and the C-STAT, LAMS, RACE, and FAST-ED scores were each associated with LVO in univariable analyses. The AUCs for C-STAT, LAMS, RACE, and FAST-ED were similar. The addition of the known AF and no anticoagulation variable did not appreciably change these AUCs. Conclusion: Although known AF with no anticoagulation was associated with LVO in patients with acute ischemic stroke, this historic feature did not improve the accuracy of existing LVO detection scales.

The Accuracy of Large Vessel Occlusion Recognition Scales in Telestroke Setting

Introduction: A significant proportion of acute ischemic stroke (AIS) patients who are evaluated through telestroke consultation are transferred to thrombectomy-capable stroke centers (TSCs) for concern of large vessel occlusion (LVO). Patient triage selection is commonly based on the clinical suspicion of LVO, which lacks specificity and could result in unnecessary transfers. In this study, we aimed to assess the accuracy of the most commonly used LVO recognition scales in telestroke setting. Methods: AIS patients transferred to TSCs for suspicion of an LVO were included in this retrospective study. Patients were evaluated by a stroke neurologist through a telestroke consult before transfer. The National Institute of Health Stroke Scale (NIHSS) score documented by the stroke neurologist was retrieved from medical records and used to calculate five other LVO recognition scales (Rapid Arterial Occlusion Evaluation Scale [RACE], Field Assessment Stroke Triage for Emergency Destination [FAST-ED], Cincinnati Prehospital Stroke Severity Scale [CPSSS], 3-item stroke scale [3I-SS], and Prehospital Acute Stroke Severity Scale [PASS]). We calculated the sensitivity, specificity, accuracy, positive and negative predictive values, false positive rate (FPR), and false negative rate (FNR) of each score using published cutoffs and then examined all possible cutoff values for each of these scales in addition to the NIHSS. Results: A total of 439 patients were included in the final analysis. A total of 48.5% of patients had an LVO confirmed on computed tomography angiogram. RACE score had the highest accuracy (78%). Overall, the five derived LVO recognition scores have at least 10% FNR. When examining all possible cutoff values, the NIHSS (cutoff of 6) had a 3% FNR but 73% FPR (false transfer). Conclusion: The use of the NIHSS and other LVO recognition scores over telestroke may result in unnecessary transfers. Better diagnostic tools that could maximize sensitivity with acceptable specificity are urgently needed.

Abstract WP293: A Prospective Validation of Stroke Network of Wisconsin (snow) Scale to Predict Large Vessel Occlusion (lvo) and Comparison With Other Stroke Scales

Background: Prior retrospective analysis confirmed that the Stroke Network of Wisconsin (SNOW) scale was highly predictive of large vessel occlusion (LVO) in patients with Acute Ischemic Stroke (AIS). In this study, we prospectively validated the SNOW scale for the identification of LVO. We also compared its accuracy to other stroke scales retrospectively applied to the same dataset. Methods: The SNOW scale consists of 3 exam elements: expressive aphasia/Speaking difficulty (S), neglect (N) and Ocular deviation (O). The scale is positive if any one of these items is present. We prospectively evaluated all acute ischemic stroke (AIS) patients who presented within 24 hours after onset at Aurora St. Luke’s Medical Center between July 2017-February 2018 and calculated the SNOW score. We retrospectively calculated Rapid Arterial Occlusion Evaluation (RACE), the Field Assessment Stroke Triage for Emergency Destination (FAST-ED), the Vision Aphasia and Neglect Scale (VAN), the Cincinnati Prehospital Stroke Severity (CPSS), the Los Angeles Motor Scale (LAMS), the Prehospital Acute Stroke Severity Scale (PASS) for all patients. The predictive performance of all scales and National Institute of Health Stroke Scale (NIHSS) cut offs ≥6 were determined and compared. LVO was defined by total occlusions involving the intracranial internal carotid artery, middle cerebral artery (M1), or basilar arteries Results: Among 344 AIS patients, 283 (82%) had vascular imaging and were included in the analysis. LVO was detected in 43 (15%). Positive SNOW scale showed: sensitivity = 0.84, specificity = 0.63, positive predictive value = 0.29, negative predictive value= 0.96, and area under the curve =0.74. SNOW scale had comparable accuracy to predict LVO as other scales and NIHSS cut offs ≥6. If LVO includes M2, positive SNOW had sensitivity of 0.85, specificity of 0.70, positive predictive value of 0.49, negative predictive value of 0.93 and area under the curve of 0.77. SNOW had the highest sensitivity but lowest specificity among other scales. Conclusion: The SNOW scale is a simple and accurate tool to help identify AIS due to LVO, and it compares favorably to the other scales evaluated. A prospective validation study of the SNOW scale in the prehospital setting is underway. .

Abstract WP288: Impact of Prehospital LVO Tools on the Delay of Care and Redistribution of Patients between Primary and Comprehensive Stroke Centers

Introduction: Several tools have been developed aimed at predicting large vessel occlusion (LVO) in the prehospital setting. If these tools are used to bypass Alteplase-but-not-thrombectomy-capable hospitals, this would speed the care for some patients, delay it for others, and unnecessarily redistribute some patients between hospitals. Methods: We examined a hypothetical scenario of 1,000 patients evaluated by EMS for possible stroke. We used data published by RACE (Rapid Arterial oCclusion Evaluation) that included 357 patients to calculate the rates of the different stroke subtypes. Ischemic stroke represented 67.2% of patients, hemorrhagic stroke 14.6%, transient ischemic attack 5.6%, and stroke mimic 12.6%. We applied the following assumptions: rate of LVO as 20% of total ischemic stroke, all patients evaluated by EMS within 3 hours from their last known well time with a rate of tPA utilization is 50%, endovascular-capable hospital is further away, similar door-to-needle (DTN) time in all hospitals, delay in DTN in false positive patients, and delay in door-to-groin time (DTG) in false negative patients. Seven tools were studied using published values for sensitivity and specificity. Results: Using no tools would lead to evaluation of all patients at the nearer hospital first, leading to delay in DTG of all 134 LVO patients, however no delay in DTN. Comparing the various tools, DTN delay would be highest with Cincinnati Prehospital Stroke Severity Scale (CPSSS; n=175) and least with 3-item stroke scale (3I-SS; n=23). DTG delay would be highest with Prehospital Acute Stroke Severity (PASS) and Field Assessment Stroke Triage for Emergency Destination (FAST-ED) (n=52 for both) and least with RACE (n=20). Redistribution of patients would be highest with CPSSS and lowest with 3I-SS (reduction in patient volume to non-thrombectomy capable hospital 63% and 16% respectively and increase in volume for the thrombectomy-capable hospital by 371% and 19% respectively). Conclusion: Current tools have a very wide variation in performance. Although some tools would likely reduce the delay in DTG time for most (but not all) LVO patients, they risk delaying care for other patients and may cause an unnecessary redistribution of patients between hospitals.

Pomona Large Vessel Occlusion Screening Tool for Prehospital and Emergency Room Settings

Background: Early identification of patients with acute ischemic strokes due to large vessel occlusions (LVO) is critical. We propose a simple risk score model to predict LVO. Method: The proposed scale (Pomona Scale) ranges from 0 to 3 and includes 3 items: gaze deviation, expressive aphasia, and neglect. We reviewed a cohort of all acute stroke activation patients between February 2014 and January 2016. The predictive performance of the Pomona Scale was determined and compared with several National Institutes of Health Stroke Scale (NIHSS) cutoffs (≥4, ≥6, ≥8, and ≥10), the Los Angeles Motor Scale (LAMS), the Cincinnati Prehospital Stroke Severity (CPSS) scale, the Vision Aphasia and Neglect Scale (VAN), and the Prehospital Acute Stroke Severity Scale (PASS). Results: LVO was detected in 94 of 776 acute stroke activations (12%). A Pomona Scale ≥2 had comparable accuracy to predict LVO as the VAN and CPSS scales and higher accuracy than Pomona Scale ≥1, LAMS, PASS, and NIHSS. A Pomona Scale ≥2 had an accuracy (area under the curve) of 0.79, a sensitivity of 0.86, a specificity of 0.70, a positive predictive value of 0.71, and a negative predictive value of 0.97 for the detection of LVO. We also found that the presence of either neglect or gaze deviation alone had comparable accuracy of 0.79 as Pomona Scale ≥2 to detect LVO. Conclusion: The Pomona Scale is a simple and accurate scale to predict LVO. In addition, the presence of either gaze deviation or neglect also suggests the possibility of LVO.

Abstract WP216: External Validation of Pomona Large Vessel Occlusion Scale at Aurora Health Care System (AHCS)

Background: The Pomona scale was developed to predict large-vessel occlusions (LVO) in patients with acute ischemic stroke (AIS). The original study showed a high accuracy of this scale. We sought to externally validate the Pomona scale in an independent cohort. Methods: Pomona scale includes 3 items: gaze deviation, expressive aphasia and neglect, each given 1 point when present. We retrospectively reviewed a large cohort of all acute stroke patients who presented within 24 hours after onset at AHCS ( 14 hospitals) between January 2015-December 2016. We calculated Pomona scale, the Vision Aphasia and Neglect Scale (VAN), the Cincinnati Prehospital Stroke Severity (CPSS), the Los Angeles Motor Scale (LAMS), the Prehospital Acute Stroke Severity Scale (PASS) for all patients. The predictive performance of all scales and several National Institute of Health Stroke Scale (NIHSS) cut offs (≥4, ≥6, ≥8, ≥10) were determined and compared. LVO was defined by total occlusions involving the intracranial internal carotid artery, middle cerebral artery (M1), or basilar arteries. Results: Among 2183 AIS patients, 1410 had vascular imaging and were included in the analysis. LVO was detected in 171 (12%). Pomona scale ≥ 1 had comparable accuracy to predict LVO as Pomona scale ≥ 2, the CPSS, and NIHSS ≥6, ≥8, and ≥10. Pomona scale ≥ 1 had higher accuracy than VAN, LAMS, PASS and NIHSS ≥ 4 (area under the receiver operating characteristics curve: Pomona ≥ 1= 0.77 as a reference; VAN=0.66, P &lt; 0.001; LAMS ≥ 4 = 0.61, P &lt; 0.001, PASS ≥ 2= 0.68, P &lt; 0.001 and NIHSS ≥ 4, P= 0.0025). A Pomona scale ≥ 1 had sensitivity of 0.79, specificity of 0.76 to predict LVO, positive predictive value of 0.31, and negative predictive value of 0.96 for the detection of LVO versus Pomona scale ≥ 2 of 0.57, 0.91, 0.47, and 0.94 and CPSS ≥ 2 of 0.64, 0.87, 0.41 and 0.95. Conclusion: In our large stroke network cohort, the Pomona scale has promising sensitivity, specificity and accuracy to predict LVO. Future prospective studies in both prehospital and emergency room settings are warranted.

Abstract WP119: Leukoaraiosis Attenuates Diagnostic Accuracy of Large Vessel Occlusion Scales

Background and Purpose: Preclinical stroke scales may help identify patients likely to have large vessel occlusion (LVO) to facilitate rapid triage to thrombectomy-capable stroke centers. Scale misclassification may result in inaccurate decisions and possible harm. Pre-existing leukoaraiosis has been shown to attenuate the association between deficit type and stroke severity. We sought to determine whether leukoaraiosis affects the predictive ability of 5 commonly used LVO scales. Materials and Methods: We retrospectively analyzed 274 consecutive stroke patients with available brain MRI and vessel imaging. The following LVO scales were used: 3 Item Stroke Scale (3I/SS), Field Assessment Stroke Triage for Emergency Destination (FAST-ED), Rapid Arterial Occlusion Evaluation (RACE), Vision, Aphasia, Neglect (VAN) score, and Cincinnati Prehospital Stroke Severity Scale (CPSSS). For diagnostic scale accuracy, we assessed sensitivity, specificity, positive predictive value, negative predictive value, and kappa. Multivariable logistic regression was used to determine the scales’ predictive ability after adjustment for leukoaraiosis and potential confounders. Results: In unadjusted analyses, all scales predicted LVO (n=46; P&lt;0.01, each), though leukoaraiosis attenuated diagnostic accuracy and was associated with more false negative diagnoses. After adjustment, the FAST-ED (OR 3.2 [1.1-9.5]; P=0.033), and RACE (OR 3.7 [1.3-10.8]; P=0.015) but not 3I/SS (OR 5.4 [0.86-33.9]); P=0.073), VAN (OR 2.5 [0.8-7.2]), and CPSSS (OR 2.8 [1.0-8.0]) predicted LVO. Conclusion: The diagnostic accuracy of the tested LVO scales was attenuated by moderate-tosevere leukoaraiosis. If confirmed, this information may aid acute decision making and the design of studies that require LVO scale screening of patients likely to have concomitant leukoaraiosis.

Leukoaraiosis Attenuates Diagnostic Accuracy of Large-Vessel Occlusion Scales.

Prehospital stroke scales may help identify patients likely to have large-vessel occlusion to facilitate rapid triage to thrombectomy-capable stroke centers. Scale misclassification may result in inaccurate decisions and possible harm. Pre-existing leukoaraiosis has been shown to attenuate the association between deficit type and stroke severity. We sought to determine whether leukoaraiosis affects the predictive ability of 5 commonly used large-vessel occlusion scales. We retrospectively analyzed 274 consecutive patients with stroke with available brain MR imaging and vessel imaging. We used the following large-vessel occlusion scales: the 3-Item Stroke Scale; Field Assessment Stroke Triage for Emergency Destination; Rapid Arterial Occlusion Evaluation; Vision, Aphasia, Neglect score; and Cincinnati Prehospital Stroke Severity Scale. For diagnostic scale accuracy, we assessed sensitivity, specificity, positive predictive value, negative predictive value, and κ. Multivariable logistic regression was used to determine the predictive ability of the scales after adjustment for leukoaraiosis and potential confounders. In unadjusted analyses, all scales predicted the presence of large-vessel occlusion (n = 46, P < .01 each), though diagnostic accuracy was attenuated among patients with moderate-to-severe leukoaraiosis. After adjustment, the Field Assessment Stroke Triage for Emergency Destination (OR = 3.2; 95% CI, 1.1-9.5; P = .033) and Rapid Arterial Occlusion Evaluation (OR = 3.7; 95% CI, 1.3-10.8; P = .015), but not the 3-Item Stroke Scale (OR = 5.4; 95% CI, 0.86-33.9; P = .073), Vision, Aphasia, Neglect score (OR = 2.5; 95% CI, 0.8-7.2), and Cincinnati Prehospital Stroke Severity Scale (OR = 2.8; 95% CI, 1.0-8.0), predicted large-vessel occlusion. The diagnostic accuracy of the tested large-vessel occlusion scales was attenuated in the presence of moderate-to-severe leukoaraiosis. This information that may aid the design of future studies that require large-vessel occlusion scale screening of patients who are likely to have concomitant leukoaraiosis.

Derivation and Validation of the Emergency Medical Stroke Assessment and Comparison of Large Vessel Occlusion Scales

This study aims to develop a simple scale to identify patients with prehospital stroke with large vessel occlusion (LVO), without losing sensitivity for other stroke types. The Emergency Medical Stroke Assessment (EMSA) was derived from the National Institutes of Health Stroke Scale (NIHSS) items and validated for prediction of LVO in a separate cohort. We compared the EMSA with the 3-item stroke scale (3I-SS), Cincinnati Prehospital Stroke Severity Scale (C-STAT), Rapid Arterial oCclusion Evaluation (RACE) scale, and Field Assessment Stroke Triage for Emergency Destination (FAST-ED) for prediction of LVO and stroke. We surveyed paramedics to assess ease of use and interpretation of scales. The combination of gaze preference, facial asymmetry, asymmetrical arm and leg drift, and abnormal speech or language yielded the EMSA. An EMSA less than 3, 75% sensitivity, and 50% specificity significantly reduced the likelihood of LVO (LR- = .489, 95% confidence interval .366-0.637) versus 3I-SS less than 4 (.866, .798-0.926). A normal EMSA, 93% sensitivity, and 47% specificity significantly reduced the likelihood of stroke (LR- = .142, .068-0.299) versus 3I-SS (.476, .330-0.688) and C-STAT (.858, .717-1.028). EMSA was rated easy to perform by 72% (13 of 18) of paramedics versus 67% (12 of 18) for FAST-ED and 6% (1 of 18) for RACE (χ2 = 27.25, P < .0001), and easy to interpret by 94% (17 of 18) versus 56% (10 of 18) for FAST-ED and 11% (2 of 18) for RACE (χ2 = 21.13, P < .0001). The EMSA has superior abilities to identify LVO versus 3I-SS and stroke versus 3I-SS and C-STAT. The EMSA has similar ability to triage patients with stroke compared with the FAST-ED and RACE, but is simpler to perform and interpret.

Large Vessel Occlusion Scales Increase Delivery to Endovascular Centers Without Excessive Harm From Misclassifications

Clinical large vessel occlusion (LVO) triage scales were developed to identify and bypass LVO to endovascular centers. However, there are concerns that scale misclassification of patients may cause excessive harm. We studied the settings where misclassifications were likely to occur and the consequences of these misclassifications in a representative stroke population. Prospective data were collected from consecutive ambulance-initiated stroke alerts at 2 stroke centers, with patients stratified into typical (LVO with predefined severe syndrome and non-LVO without) or atypical presentations (opposite situations). Five scales (Rapid Arterial Occlusion Evaluation [RACE], Los Angeles Motor Scale [LAMS], Field Assessment Stroke Triage for Emergency Destination [FAST-ED], Prehospital Acute Stroke Severity scale [PASS], and Cincinnati Prehospital Stroke Severity Scale [CPSSS]) were derived from the baseline National Institutes of Health Stroke Scale scored by doctors and analyzed for diagnostic performance compared with imaging. Of a total of 565 patients, atypical presentations occurred in 31 LVO (38% of LVO) and 50 non-LVO cases (10%). Most scales correctly identified >95% of typical presentations but <20% of atypical presentations. Misclassification attributable to atypical presentations would have resulted in 4 M1/internal carotid artery occlusions, with National Institutes of Health Stroke Scale score ≥6 (5% of LVO) being missed and 9 non-LVO infarcts (5%) bypassing the nearest thrombolysis center. Atypical presentations accounted for the bulk of scale misclassifications, but the majority of these misclassifications were not detrimental, and use of LVO scales would significantly increase timely delivery to endovascular centers, with only a small proportion of non-LVO infarcts bypassing the nearest thrombolysis center. Our findings, however, would require paramedics to score as accurately as doctors, and this translation is made difficult by weaknesses in current scales that need to be addressed before widespread adoption.

Abstract TP251: Pomona Large Vessel Occlusion Scale for Pre-hospital and Emergency Room Settings

Background: Early detection of acute stroke with large vessel occlusion (LVO) in both pre-hospital and emergency room settings results in favorable clinical outcomes. There is still no universal guideline for LVO screening. Method: We proposed that the presence of any of the following signs (Pomona scale): gaze deviation, expressive aphasia or neglect has a high sensitivity and accuracy to predict LVO. We reviewed a historical cohort of all acute stroke activation patients at Pomona Valley Hospital during February 2014 to January 2016. We tested Pomona scale in both groups. The predictive performance of Pomona scale was compared with different NIHSS cutoffs ( ≥4, ≥6, ≥8, ≥10), Los Angeles Motor Scale (LAMS), Cincinnati Prehospital Stroke Severity (CPSS) scale, Vision Aphasia and Neglect scale (VAN) and Prehospital Acute Stroke Severity (PASS) scale. Results: LVO was detected in 129 of the 777 acute stroke activation (17%). Two hundred and forty-two patients had nonLVO stroke (31%). NIHSS ≥4 and Pomona scale had highest sensitivity (0.99 and 0.98 respectively) to predict LVO. LAM scale had lowest sensitivity (0.68). Pomona scale had moderate accuracy (0.61) which was comparable with VAN (0.66) and PASS (0.67). NIHSS ≥4 had the least accuracy (0.28). When Pomona scale was combined with arm weakness, it had highest accuracy (0.77) and high sensitivity (0.92) to predict LVO in acute ischemic stroke subgroup. Using various NIHSS cut off to screen for LVO had lower accuracy than using other LVO screening tools. Conclusion: Pomona scale is very sensitive to predict LVO. It may be used as a screening tool for LVO in emergency room setting. Combination of arm weakness and Pomona scale may be used as a Pre-hospital LVO screening with moderately high accuracy.

Abstract TP225: Predicting Large Vessel Occlusion in the Real World: Use of the Cincinnati Pre-hosptial Stroke Severity Score in Patients with Suspected Acute Ischemic Stroke

Background: The Colorado Stroke Advisory Board (COSAB) asked three Joint Commission (JC) comprehensive stroke centers (CSC) and one primary stroke center (PSC) to assist with determining the usefulness of the Cincinnati Pre-Hospital Stroke Severity Score (CPSSS) in predicting large vessel occlusion (LVO) in patients with acute stroke symptoms. Purpose: The purpose of the study was to determine the real world applicability of the CPSSS in predicting LVO. Methods: CPSSS and LVO data was collected by stroke coordinators at three CSCs and one PSC for all patients brought to their respective emergency departments via local emergency medical services (EMS) from June 2016 to July 2016 as stroke alerts. The CPSSS was calculated retrospectively using the initial documented neurological exam and LVO was determined by initial computed tomography (CT) imaging results or physician notes in the electronic medical record. Results: Our study included 235 patients that were brought to 4 certified stroke centers in the Denver metropolitan area during a two month period in 2016. Eighty percent of patients (N=187/235) correctly screened negative on the CPSSS. Ten percent (N=23/235) of patients screened positive and were later determined to have LVO based on initial imaging. Four patients went on for endovascular treatment at a CSC that initially screened negative using the CPSSS. Nine percent (N=21/235) of patients screened false-positive for LVO. Top reasons for false positive CPSSS include intracerebral hemorrhage, altered mental status, seizure, and brain stem stroke. Conclusion: CPSSS is a reasonable screening tool to assess for LVO. More study is recommended to determine how to avoid missing LVO in stroke patients with mild symptoms on initial presentation.

Abstract TP253: A Novel Prehospital Scale to Predict Candidates for Acute Stroke Thrombectomy : The Fukuoka Acute Stroke ThrombEctomy pRediction (FASTER) Scale

Background: We aimed to design a prehospital scale to predict candidates for endovascular thrombectomy (CET) in patients with acute ischemic stroke (AIS). Materials and methods: In the Fukuoka Stroke Registry, we identified 3,470 patients with AIS who were transferred by emergency medical service within 24 hours of stroke onset and underwent intracranial vessel evaluation on admission from September 2007 to December 2015. CET were defined as patients with causative occlusion of internal carotid artery, middle cerebral artery, or basilar artery, and National Institute of Health Stroke Scale (NIHSS) score ≥ 6. The Fukuoka Acute Stroke ThrombEctomy pRediction (FASTER) scale was developed with NIHSS items based on the predictive importance derived from random forest analysis to predict CET. The discriminative performance was compared with other published scales for large vessel occlusion. Results: The FASTER scale was designed comprising of 4 NIHSS items : one point each was given for extinction and inattention (NIHSS subscore ≥ 1), best gaze (≥ 1), best language (≥ 1), and motor arm (≥ 2). Receiver operator curves demonstrated that the area under the curve of the FASTER scale was significantly larger than that of the Cincinnati Prehospital Stroke Severity Scale (0.907 vs 0.881, p&lt;0.001), and not significantly different from that of the Rapid Arterial oCclusion Evaluation scale (vs 0.910, p= 0.68). The FASTER scale score ≥2 showed sensitivity of 88.4%, specificity 82.3%, positive predictive value 51.3%, and negative predictive value 97.1% for detecting CET. Conclusion: The FASTER scale is a simple and promising tool that can identify CET in the prehospital setting.

Field Assessment Stroke Triage for Emergency Destination

Patients with large vessel occlusion strokes (LVOS) may be better served by direct transfer to endovascular capable centers avoiding hazardous delays between primary and comprehensive stroke centers. However, accurate stroke field triage remains challenging. We aimed to develop a simple field scale to identify LVOS. The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scale was based on items of 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. LVOS were defined by total occlusions involving the intracranial internal carotid artery, middle cerebral artery-M1, middle cerebral artery-2, or basilar arteries. Patients with partial, bihemispheric, and anterior+posterior circulation occlusions were excluded. Receiver operating characteristic curve, sensitivity, specificity, positive predictive value, and negative predictive value of FAST-ED were compared with the NIHSS, Rapid Arterial Occlusion Evaluation (RACE) scale, and Cincinnati Prehospital Stroke Severity (CPSS) scale. LVO was detected in 240 of the 727 qualifying patients (33%). FAST-ED had comparable accuracy to predict LVO to the NIHSS and higher accuracy than RACE and CPSS (area under the receiver operating characteristic curve: FAST-ED=0.81 as reference; NIHSS=0.80, P=0.28; RACE=0.77, P=0.02; and CPSS=0.75, P=0.002). A FAST-ED ≥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 ≥5 of 0.55, 0.87, 0.68, and 0.79, and CPSS ≥2 of 0.56, 0.85, 0.65, and 0.78, respectively. FAST-ED is a simple scale that if successfully validated in the field, it may be used by medical emergency professionals to identify LVOS in the prehospital setting enabling rapid triage of patients.

Clinical Scales Do Not Reliably Identify Acute Ischemic Stroke Patients With Large-Artery Occlusion.

It remains debated whether clinical scores can help identify acute ischemic stroke patients with large-artery occlusion and hence improve triage in the era of thrombectomy. We aimed to determine the accuracy of published clinical scores to predict large-artery occlusion. We assessed the performance of 13 clinical scores to predict large-artery occlusion in consecutive patients with acute ischemic stroke undergoing clinical examination and magnetic resonance or computed tomographic angiography ≤6 hours of symptom onset. When no cutoff was published, we used the cutoff maximizing the sum of sensitivity and specificity in our cohort. We also determined, for each score, the cutoff associated with a false-negative rate ≤10%. Of 1004 patients (median National Institute of Health Stroke Scale score, 7; range, 0-40), 328 (32.7%) had an occlusion of the internal carotid artery, M1 segment of the middle cerebral artery, or basilar artery. The highest accuracy (79%; 95% confidence interval, 77-82) was observed for National Institute of Health Stroke Scale score ≥11 and Rapid Arterial Occlusion Evaluation Scale score ≥5. However, these cutoffs were associated with false-negative rates >25%. Cutoffs associated with an false-negative rate ≤10% were 5, 1, and 0 for National Institute of Health Stroke Scale, Rapid Arterial Occlusion Evaluation Scale, and Cincinnati Prehospital Stroke Severity Scale, respectively. Using published cutoffs for triage would result in a loss of opportunity for ≥20% of patients with large-artery occlusion who would be inappropriately sent to a center lacking neurointerventional facilities. Conversely, using cutoffs reducing the false-negative rate to 10% would result in sending almost every patient to a comprehensive stroke center. Our findings, therefore, suggest that intracranial arterial imaging should be performed in all patients with acute ischemic stroke presenting within 6 hours of symptom onset.

External Validation of the Cincinnati Prehospital Stroke Severity Scale

The Cincinnati Prehospital Stroke Severity Scale (CPSSS) was recently developed to predict large-vessel occlusions (LVOs) in patients with acute ischemic stroke (AIS). In its derivation study, which consisted of patients enrolled in thrombolysis and endovascular therapy trials, the CPSSS had excellent discriminatory performance. We sought to externally validate the CPSSS in an independent cohort. Using our institution's prospective stroke registry, we calculated CPSSS scores for all patients diagnosed with AIS at Weill Cornell Medical Center in 2013 and 2014. The primary outcome was presence of LVO and the secondary outcome was a National Institutes of Health Stroke Scale (NIHSS) score of 15 or higher. Harrell's c-statistic was calculated to determine the CPSSS score's discriminatory performance. Using the previously defined cut-point of 2 or higher (range 0-4), we evaluated the test properties of the CPSSS for predicting study outcomes. Among 751 patients with AIS, 664 had vessel imaging and were included in the final analysis. Of these patients, 80 (14.2%) had LVOs and 117 (17.6%) had an NIHSS score of 15 or higher. The median CPSSS score was 0 (interquartile range 0-1) and 133 patients (20%) had scores of 2 or higher. c-statistic was .85 (95% confidence interval [CI] .81-.90) for predicting LVO and .94 (95% CI .92-.97) for predicting an NIHSS score of 15 or higher. Using a cut-point of 2 or higher, the CPSSS was 70.0% sensitive and 86.8% specific for predicting LVO, and 87.2% sensitive and 94.3% specific for predicting an NIHSS score of 15 or higher. In a cohort of patients with AIS treated at a tertiary-care stroke center, the CPSSS had reasonable sensitivity and specificity for predicting LVO and severe stroke. Future studies should aim to prospectively validate the score in emergency responders.