Prehospital Acute Stroke Severity Research Articles

Retracted: Modified Prehospital Acute Stroke Severity (mPASS) Scale to Predict Emergent Large Arterial Occlusion.

[This retracts the article DOI: 10.1155/2021/5568696.].

Sex Differences in Prehospital Identification of Large Vessel Occlusion in Patients With Suspected Stroke.

Differences in clinical presentation of acute ischemic stroke between men and women may affect prehospital identification of anterior circulation large vessel occlusion (aLVO). We assessed sex differences in diagnostic performance of 8 prehospital scales to detect aLVO. We analyzed pooled individual patient data from 2 prospective cohort studies (LPSS [Leiden Prehospital Stroke Study] and PRESTO [Prehospital Triage of Patients With Suspected Stroke Study]) conducted in the Netherlands between 2018 and 2019, including consecutive patients ≥18 years suspected of acute stroke who presented within 6 hours after symptom onset. Ambulance paramedics assessed clinical items from 8 prehospital aLVO detection scales: Los Angeles Motor Scale, Rapid Arterial Occlusion Evaluation, Cincinnati Stroke Triage Assessment Tool, Cincinnati Prehospital Stroke Scale, Prehospital Acute Stroke Severity, gaze-face-arm-speech-time, Conveniently Grasped Field Assessment Stroke Triage, and Face-Arm-Speech-Time Plus Severe Arm or Leg Motor Deficit. We assessed the diagnostic performance of these scales for identifying aLVO at prespecified cut points for men and women. Of 2358 patients with suspected stroke (median age, 73 years; 47% women), 231 (10%) had aLVO (100/1114 [9%] women and 131/1244 [11%] men). The area under the curve of the scales ranged from 0.70 (95% CI, 0.65-0.75) to 0.77 (95% CI, 0.73-0.82) in women versus 0.69 (95% CI, 0.64-0.73) to 0.75 (95% CI, 0.71-0.79) in men. Positive predictive values ranged from 0.23 (95% CI, 0.20-0.27) to 0.29 (95% CI, 0.26-0.31) in women versus 0.29 (95% CI, 0.24-0.33) to 0.37 (95% CI, 0.32-0.43) in men. Negative predictive values were similar (0.95 [95% CI, 0.94-0.96] to 0.98 [95% CI, 0.97-0.98] in women versus 0.94 [95% CI, 0.93-0.95] to 0.96 [95% CI, 0.94-0.97] in men). Sensitivity of the scales was slightly higher in women than in men (0.53 [95% CI, 0.43-0.63] to 0.76 [95% CI, 0.68-0.84] versus 0.49 [95% CI, 0.40-0.57] to 0.63 [95% CI, 0.55-0.73]), whereas specificity was lower (0.79 [95% CI, 0.76-0.81] to 0.87 [95% CI, 0.84-0.89] versus 0.82 [95% CI, 0.79-0.84] to 0.90 [95% CI, 0.88-0.91]). Rapid arterial occlusion evaluation showed the highest positive predictive values in both sexes (0.29 in women and 0.37 in men), reflecting the different event rates. aLVO scales show similar diagnostic performance in both sexes. The rapid arterial occlusion evaluation scale may help optimize prehospital transport decision-making in men as well as in women with suspected stroke.

Prehospital stroke scales outperform National Institutes of Health Stroke Scale in predicting large vessel occlusion in a large academic telestroke network.

Prehospital telestroke evaluations may improve stroke triage compared to paramedic-applied large vessel occlusion scales, but ambulance-based video National Institutes of Health Stroke Scale assessments are challenging. The accuracy of telestroke-administered large vessel occlusion scales has not been investigated, so we sought to evaluate this further. This retrospective study included all in-hospital telestroke encounters in a large academic telestroke network from 2019 to 2020. We retrospectively calculated seven large vessel occlusion scales using the in-hospital telestroke National Institutes of Health Stroke Scale (Rapid Arterial oCclusion Evaluation, Cincinnati Stroke Triage Assessment Tool, Field Assessment Stroke Triage for Emergency Destination, 3-Item Stroke Scale, Prehospital Acute Stroke Severity, Vision-Aphasia-Neglect, and Gaze-Face-Arm-Speech-Time). Diagnostic performance was assessed via sensitivity, specificity, negative predictive value, positive predictive value, positive likelihood ratio, negative likelihood ratio, and accuracy using established scale thresholds. These results were compared to the National Institutes of Health Stroke Scale at thresholds of 6, 8, and 10. The area under curve was calculated using c-statistics by treating scales as continuous variables. A total of 625 patients were included; 111 (17.8%) patients had an anterior large vessel occlusion, 118 (18.9%) patients had any large vessel occlusion, and 182 (29.1%) patients had stroke mimic diagnosis. The mean age (SD) was 67.9 (15.9), 48.3% were female, and 93.4% were white. The Mean National Institutes of Health Stroke Scale (SD) was 14.9 (8.4) for patients with anterior large vessel occlusion, 4.7 (5.0) for patients with non-large vessel occlusion ischemic stroke, and 4.4 (5.8) for stroke mimic (p < 0.001). Compared to the National Institutes of Health Stroke Scale, Field Assessment Stroke Triage for Emergency Destination, and Rapid Arterial oCclusion Evaluation scales demonstrated higher accuracy and area under curve for large vessel occlusion detection. Both the Field Assessment Stroke Triage for Emergency Destination and Rapid Arterial oCclusion Evaluation scales outperformed the National Institutes of Health Stroke Scale for large vessel occlusion detection in patients evaluated by in-hospital telestroke. These scales may be valid alternatives to the National Institutes of Health Stroke Scale examination in this setting.

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.

Inter-Rater Agreement on Cincinnati Prehospital Stroke Scale (CPSS) and Prehospital Acute Stroke Severity Scale (PASS) Between EMS Providers, Neurology Residents and Neurology Consultants.

To examine the agreement between emergency medical service (EMS) providers, neurology residents and neurology consultants, using the Cincinnati Prehospital Stroke Scale (CPSS) and the Prehospital Acute Stroke Severity Scale (PASS). Patients with stroke, transient ischemic attack (TIA) and stroke mimic were included upon primary stroke admission or during rehabilitation. Patients were included from June 2018 to September 2019. Video recordings were made of patients being assessed with CPSS and PASS. The recordings were later presented to the healthcare professionals. To determine relative and absolute interrater reliability in terms of inter-rater agreement (IRA), we used generalisability theory. Group-level agreement was determined against a gold standard and presented as an area under the curve (AUC). The gold standard was a consensus agreement between two neurology consultants. A total of 120 patient recordings were assessed by 30 EMS providers, two neurology residents and two neurology consultants. Using the CPSS and the PASS, a total of 1,800 assessments were completed by EMS providers, 240 by neurology residents and 240 by neurology consultants. The overall relative and absolute IRA for all items combined from the CPSS and PASS score was 0.84 (95% CI 0.80; 0.87) and 0.81 (95% CI 0.77; 0.85), respectively. Using the CPSS, the agreement on a group-level resulted in AUCs of 0.83 (95% CI 0.78; 0.88) for the EMS providers and 0.86 (95% CI 0.82; 0.90) for the neurology residents when compared with the gold standard. Using the PASS, the AUC was 0.82 (95% CI 0.77; 0.87) for the EMS providers and 0.88 (95% CI 0.84; 0.93) for the neurology residents. The high relative and absolute inter-rater agreement underpins a high robustness/generalisability of the two scales. A high agreement exists across individual raters and different groups of healthcare professionals supporting widespread applicability of the stroke scales.

Design and validation of a new scale for prehospital evaluation of stroke and large vessel occlusion.

Background:Rapid recognition of acute stroke and large vessel occlusion (LVO) is essential in prehospital triage for timely reperfusion treatment.Objective:This study aimed to develop and validate a new screening tool for both stroke and LVO in an urban Chinese population.Methods:This study included patients with suspected stroke who were transferred to our hospital by emergency medical services between July 2017 and June 2021. The population was randomly partitioned into training (70%) and validation (30%) groups. The Staring-Hypertension-atrIal fibrillation-sPeech-weakneSs (SHIPS) scale, consisting of both clinical and medical history information, was generated based on multivariate logistic models. The predictive ability of the SHIPS scale was evaluated and compared with other scales using receiver operating characteristic (ROC) curve comparison analysis.Results:A total of 400 patients were included in this analysis. In the training group (n = 280), the SHIPS scale showed a sensitivity of 90.4% and specificity of 60.8% in predicting stroke and a sensitivity of 75% and specificity of 61.5% in predicting LVO. In the validation group (n = 120), the SHIPS scale was not inferior to Stroke 1-2-0 (p = 0.301) in predicting stroke and was significantly better than the Cincinnati Stroke Triage Assessment Tool (C-STAT; formerly CPSSS) and the Prehospital Acute Stroke Severity scale (PASS) (all p < 0.05) in predicting LVO. In addition, including medical history in the scale was significantly better than using symptoms alone in detecting stroke (training group, 0.853 versus 0.818; validation group, 0.814 versus 0.764) and LVO (training group, 0.748 versus 0.722; validation group, 0.825 versus 0.778).Conclusion:The SHIPS scale may serve as a superior screening tool for stroke and LVO identification in prehospital triage. Including medical history in the SHIPS scale improves the predictive value compared with clinical symptoms alone.

Modified Prehospital Acute Stroke Severity (mPASS) Scale to Predict Emergent Large Arterial Occlusion.

Introduction To date, identifying emergent large vessel occlusion (ELVO) patients in the prehospital stage is important but still challenging. In this present study, we aimed to design a modified prehospital acute stroke severity (mPASS) scale to identify ELVO patients and compared the scale to the PASS scale which has been published. Methods We retrospectively evaluated a consecutive cohort of acute ischemic stroke (AIS) in our stroke unit who visited the emergercy department. These patients underwent CT angiography (CTA), MR angiography (MRA), or digital subtraction angiography (DSA) at admission. The mPASS scale was calculated based on the National Institutes of Health Stroke Scale (NIHSS) items retrospectively, including the level of consciousness commands, gaze, arm weakness, and aphasia/dysarthria. Receiver operating characteristic (ROC) analysis was used to obtain the area under the curve (AUC) of the mPASS scale, NIHSS, and PASS scale. U-statistics was used to compare the AUC of the mPASS scale to the NIHSS and PASS scale. Results A total of 382 AIS patients were enrolled. The AUC and specificity of the mPASS scale (0.92, 84.4) were all higher than those of the PASS scale. Cortical symptoms such as gaze palsy and consciousness disorder were more specific indicators for ELVO than motor deficits. Conclusions The mPASS scale had a better discrimination for identifying ELVO than the PASS scale in our retrospective cohort. It might predict ELVO in an effective and simple way for paramedics in the prehospital triage stage or emergency stage. Moreover, cortical symptoms might have relatively high specificities to predict ELVO on their own.

Comparison of eight prehospital stroke scales to detect intracranial large-vessel occlusion in suspected stroke (PRESTO): a prospective observational study

Due to the time-sensitive effect of endovascular treatment, rapid prehospital identification of large-vessel occlusion in individuals with suspected stroke is essential to optimise outcome. Interhospital transfers are an important cause of delay of endovascular treatment. Prehospital stroke scales have been proposed to select patients with large-vessel occlusion for direct transport to an endovascular-capable intervention centre. We aimed to prospectively validate eight prehospital stroke scales in the field. We did a multicentre, prospective, observational cohort study of adults with suspected stroke (aged ≥18 years) who were transported by ambulance to one of eight hospitals in southwest Netherlands. Suspected stroke was defined by a positive Face-Arm-Speech-Time (FAST) test. We included individuals with blood glucose of at least 2·5 mmol/L. People who presented more than 6 h after symptom onset were excluded from the analysis. After structured training, paramedics used a mobile app to assess items from eight prehospital stroke scales: Rapid Arterial oCclusion Evaluation (RACE), Los Angeles Motor Scale (LAMS), Cincinnati Stroke Triage Assessment Tool (C-STAT), Gaze-Face-Arm-Speech-Time (G-FAST), Prehospital Acute Stroke Severity (PASS), Cincinnati Prehospital Stroke Scale (CPSS), Conveniently-Grasped Field Assessment Stroke Triage (CG-FAST), and the FAST-PLUS (Face-Arm-Speech-Time plus severe arm or leg motor deficit) test. The primary outcome was the clinical diagnosis of ischaemic stroke with a proximal intracranial large-vessel occlusion in the anterior circulation (aLVO) on CT angiography. Baseline neuroimaging was centrally assessed by neuroradiologists to validate the true occlusion status. Prehospital stroke scale performance was expressed as the area under the receiver operating characteristic curve (AUC) and was compared with National Institutes of Health Stroke Scale (NIHSS) scores assessed by clinicians at the emergency department. This study was registered at the Netherlands Trial Register, NL7387. Between Aug 13, 2018, and Sept 2, 2019, 1039 people (median age 72 years [IQR 61-81]) with suspected stroke were identified by paramedics, of whom 120 (12%) were diagnosed with aLVO. Of all prehospital stroke scales, the AUC for RACE was highest (0·83, 95% CI 0·79-0·86), followed by the AUC for G-FAST (0·80, 0·76-0·84), CG-FAST (0·80, 0·76-0·84), LAMS (0·79, 0·75-0·83), CPSS (0·79, 0·75-0·83), PASS (0·76, 0·72-0·80), C-STAT (0·75, 0·71-0·80), and FAST-PLUS (0·72, 0·67-0·76). The NIHSS as assessed by a clinician in the emergency department did somewhat better than the prehospital stroke scales with an AUC of 0·86 (95% CI 0·83-0·89). Prehospital stroke scales detect aLVO with acceptable-to-good accuracy. RACE, G-FAST, and CG-FAST are the best performing prehospital stroke scales out of the eight scales tested and approach the performance of the clinician-assessed NIHSS. Further studies are needed to investigate whether use of these scales in regional transportation strategies can optimise outcomes of patients with ischaemic stroke. BeterKeten Collaboration and Theia Foundation (Zilveren Kruis).

Comparison of Prehospital Scales for Predicting Large Anterior Vessel Occlusion in the Ambulance Setting

The efficacy of endovascular thrombectomy (EVT) for symptomatic large anterior vessel occlusion (sLAVO) sharply decreases with time. Because EVT is restricted to comprehensive stroke centers, prehospital triage of patients with acute stroke codes for sLAVO is crucial, and although several prediction scales are already in use, external validation, head-to-head comparison, and feasibility data are lacking. To conduct external validation and head-to-head comparisons of 7 sLAVO prediction scales in the emergency medical service (EMS) setting and to assess scale feasibility by EMS paramedics. This prospective cohort study was conducted between July 2018 and October 2019 in a large urban center in the Netherlands with a population of approximately 2 million people and included 2 EMSs, 3 comprehensive stroke centers, and 4 primary stroke centers. Participants were consecutive patients aged 18 years or older for whom an EMS-initiated acute stroke code was activated. Of 2812 acute stroke codes, 805 (28.6%) were excluded, because no application was used or no clinical data were available, leaving 2007 patients included in the analyses. Applications with clinical observations filled in by EMS paramedics for each acute stroke code enabling reconstruction of the following 7 prediction scales: Los Angeles Motor Scale (LAMS); Rapid Arterial Occlusion Evaluation (RACE); Cincinnati Stroke Triage Assessment Tool; Prehospital Acute Stroke Severity (PASS); gaze-face-arm-speech-time; Field Assessment Stroke Triage for Emergency Destination; and gaze, facial asymmetry, level of consciousness, extinction/inattention. Planned primary and secondary outcomes were sLAVO and feasibility rates (ie, the proportion of acute stroke codes for which the prehospital scale could be reconstructed). Predictive performance measures included accuracy, sensitivity, specificity, the Youden index, and predictive values. Of 2007 patients who received acute stroke codes (mean [SD] age, 71.1 [14.9] years; 1021 [50.9%] male), 158 (7.9%) had sLAVO. Accuracy of the scales ranged from 0.79 to 0.89, with LAMS and RACE scales yielding the highest scores. Sensitivity of the scales ranged from 38% to 62%, and specificity from 80% to 93%. Scale feasibility rates ranged from 78% to 88%, with the highest rate for the PASS scale. This study found that all 7 prediction scales had good accuracy, high specificity, and low sensitivity, with LAMS and RACE being the highest scoring scales. Feasibility rates ranged between 78% and 88% and should be taken into account before implementing a scale.

Prehospital Triage of Patients with Suspected Stroke (PRESTO): A Prospective In-Field Validation of Eight Prehospital Stroke Scales to Detect Intracranial Large Vessel Occlusion

Background: Due to the time-sensitive effect of endovascular treatment (EVT), rapid prehospital identification of large vessel occlusion (LVO) in suspected stroke patients is essential to optimize outcome. Inter-hospital transfers are an important cause of delay of EVT. Prehospital stroke scales have been proposed to select patients with LVO for direct transport to an endovascular-capable intervention centre. We aimed to prospectively validate eight prehospital stroke scales in the field. Methods: In a multi-centre prospective observational cohort study, we included suspected stroke patients transported by ambulance in the Southwest Netherlands. Paramedics assessed items from eight prehospital stroke scales: Rapid Arterial oCclusion Evaluation (RACE), Los Angeles Motor Scale (LAMS), Cincinnati Stroke Triage Assessment Tool (C-STAT), Gaze-Face-Arm-Speech-Time (G-FAST), Prehospital Acute Stroke Severity (PASS), Cincinnati Prehospital Stroke Scale (CPSS), Conveniently-Grasped Field Assessment Stroke Triage (CG-FAST), and the FAST PLUS Test. Patients that presented beyond six hours from symptom onset were excluded. Primary outcome was the clinical diagnosis of ischaemic stroke with a proximal intracranial LVO in the anterior circulation (aLVO) on CT-angiography. Prehospital stroke scale performance was expressed as the area under the receiver operating characteristic curve (AUC) and was compared with National Institute of Health Stroke Scale (NIHSS) scores assessed by physicians at the emergency department. Findings: We included 1039 patients, of which 121 patients (12%) were diagnosed with aLVO. AUCs for the prehospital stroke scales ranged from 0·69 (FAST PLUS) to 0·82 (RACE). The performance of RACE was not significantly different from G-FAST (AUC=0·80, p=0·14) and CG-FAST (AUC=0·80, p=0·09), but was significantly different from the other scales (p-values<0·05). The NIHSS performed somewhat better (AUC 0·86, p-values<0·05). Interpretation: Prehospital stroke scales detect aLVO with good accuracy and approach the performance of the physician-assessed NIHSS. RACE is the best performing prehospital stroke scale, but does not differ significantly from G-FAST and CG-FAST. Trial Registration: This study was registered at the Netherlands Trial Register (www.trialregister.nl), NL7387 Funding: BeterKeten collaboration and Theia Foundation (Zilveren Kruis) Declaration of Interests: Diederik Dippel and Aad van der Lugt report funding from the Dutch Heart Foundation, Brain Foundation Netherlands, The Netherlands Organisation for Health Research and Development, Health Holland Top Sector Life Sciences & Health, and unrestricted grants from Penumbra Inc., Stryker, Stryker European Operations BV, Medtronic, Thrombolytic Science, LLC and Cerenovus for research, all paid to institution. Pieter Jan van Doormaal reports funding from Stryker, paid to institution and an unrestricted fee from Bayer. All other authors declare no conflict of interest. Ethics Approval Statement: This study was conducted in accordance with the Dutch Agreement on Medical Treatment Act and the European General Data Protection Regulation. The Institutional Review Board of the Erasmus MC University Medical Centre has reviewed the study protocol and confirmed that the Dutch Medical Research Involving Human Subjects Act is not applicable. Because our study met the exceptions of informed consent regulations, the need for informed consent was waived. Patients or their relatives were informed about the study and could withdraw from the study through an opt-out system.

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 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.

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. .

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.

Evaluation of NIHSS-Onset to Groin Time (OGT) and Prehospital Acute Stroke Severity Scale (PASS)-OGT scores in prediction of outcomes after Endovascular Treatment in Acute Ischemic Stroke patients: A Retrospective Single-Center Study (P1.272)

Evaluation of NIHSS-Onset to Groin Time (OGT) and Prehospital Acute Stroke Severity Scale (PASS)-OGT scores in prediction of outcomes after Endovascular Treatment in Acute Ischemic Stroke patients: A Retrospective Single-Center Study (P1.272)

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 TMP74: Evaluation of NIHSS-Onset to Groin Time and Prehospital Acute Stroke Severity Scale-onset to Groin Time Scores in Prediction of Outcomes After Endovascular Treatment in Acute Ischemic Stroke Patients: A Retrospective Single-center Study

Background: Prehospital triage tools are essential to identify large vessel occlusion (LVO) in order to triage patients to a comprehensive stroke center for timely endovascular treatment (ET). Prehospital Acute Stroke Severity Scale (PASS) (score range 0-3) was recently identified as a valuable tool to predict LVO. Several studies have shown that in patients treated with IV tPA, a score calculated by multiplying admission NIHSS by the time from symptom onset to tPA treatment (in hours) can predict outcome. In our study, we applied similar concept for patients with LVO who underwent successful ET. Methods: We retrospectively reviewed all LVO patients between January 2015 and June 2016 who received ET. We analyzed the association of time of symptom onset to groin time (OGT), NIHSS, PASS, NIHSS-OGT, and PASS-OGT with modified Rankin scale (mRS) at the time of discharge. Results: Fifty-four patients underwent ET during the study period. Patients with posterior circulation LVO and those treated after 6 hours from last known normal were excluded. A total of 34 patients were left for final analysis. Patients with a good outcome (mRS ≤2) had an average NIHSS-OGT score of 43.2 (95% CI: 29.7-56.8) and PASS-OGT score of 5.52 (95% CI: 4.48-6.56). Patient’s with poor to miserable outcomes (mRS 3-6) average NIHSS-OGT 84.7 (95% CI: 72.8-96.6) and PASS-OGT average 9.8 (95% CI: 8.3-11.2). For NIHSS-OGT cut off of 55 the sensitivity and specificity was 0.75 and 0.85 respectively; diagnostic odds ratio 16.5 (96% CI: 2.41-112.83). For PASS-OGT cut off of 6.5 the sensitivity and specificity were 0.88 and 0.76 respectively; diagnostic odds ratio 23.33 (95% CI: 2.37-229.33). The wide confidence intervals can be attributed to small sample size. Conclusion: Our study indicates NIHSS–OGT and PASS-OGT scores have a linear relationship with discharge mRS and can reliably predict early clinical outcomes after ET. Further confirmation with randomized control trials is needed.

Abstract WP268: Evaluation and Validation of Prehospital Acute Stroke Severity Scale to Predict Large Vessel Occlusion in Patients with Proven Large Vessel Occlusion; Single Center Study in US

Background: In 2015 guidelines regarding endovascular treatment (ET) of Large Vessel Occlusion (LVO) in acute ischemic stroke (AIS) were changed, leading to more patients being transferred to comprehensive stroke centers (CSC) for ET in selected patients, sometimes bypassing primary stroke centers. In the era of ET, there is a need for a simple yet sensitive pre-hospital tool to triage appropriate patients to CSCs. Many prehospital stroke scales predicting LVO are not in widespread clinical use because they are complex and not reliable. A recently published Denmark study demonstrated the PASS tool (Score range 0-3) for detecting LVO where a score of ≥2 was considered to be optimal in predicting LVO with sensitivity of 0.66. Methods: A retrospective analysis of AIS patients with confirmed anterior circulation LVO by catheter-based cerebral angiography between January 2015 and June 2016 was conducted. PASS scores were calculated and correlated with NIHSS to assess for severity of the stroke. Results: Fifty-four patients received ET during the study period. Those who had posterior circulation LVO were excluded, leaving 44 patients for final analysis. Only 5 (11.4%) patients had PASS score of &lt;2 while 39 patients (88.6 %) had a score of ≥2 showing sensitivity of 0.89 for those patients with LVO. Average NIHSS scores were 11 (95% CI 6.6-15) for PASS &lt;2 and 20 (95% CI 18.5-22.5) for PASS ≥2 (p value 0.005). Conclusion: The PASS tool is simple, quick, and easy to perform and has high sensitivity in AIS patients with LVO. To assess its value and efficacy in real time it should be implemented into EMS systems and be performed in the pre-hospital setting.