3-item stroke scale for large vessel occlusion associated with improved rates of endovascular stroke treatment

1. Endovascular therapy, a stroke reperfusion technique, was performed 2.8-fold more often after a 3-item stroke scale was installed as protocol in Chicago to triage likely large vessel occlusion patients to comprehensive stroke centers instead of general stroke centers.

Evidence Rating Level: 2 (Good)

Study Rundown: In large vessel occlusion (LVO) stroke, time to reperfusion by endovascular therapy (EVT) is an important predictor of outcome. LVO scales could help identify acute ischemic stroke (AIS) patients with probable LVO to transfer them to a comprehensive stroke center (CSC). Various Chicago medical and EMS services developed the 3-item stroke scale (3I-SS) to screen for LVO AIS. The 3I-SS assesses (1) level of consciousness, (2) gaze, and (3) motor response as 0 (normal), 1 (moderate deficit), or 2 (severe deficit), where a total of 4 suggests anterior circulation LVO. In this study, likely stroke patients were assessed with the 3I-SS and the high risk of LVO patients (>3) were transported to the closest CSC. Hospitals reported the demographics, medical history, time of symptoms, time of arrival, thrombolytic drug administration, EVT, diagnosis of LVO, and discharge date for patients that were eventually confirmed to have AIS. The EVT rates from 9 months before the 3I-SS protocol was installed and 9 months after were compared. Participants from before and after implementation had similar demographic characteristics, symptom onset to hospital arrival time, rates and time of tissue plasminogen activator administration, and rates of discharge home. EVT was performed nearly 3-fold more after 3I-SS implementation. This increase occurred in a step-wise manner in the month of 3I-SS implementation. There was more EVT performed in the group 6 hours after symptom onset, but not those 6 – 24 hours after symptom onset, suggesting the protocol change affected acute individuals. A strength of this study was the coordination of multiple CSCs to have a simultaneous change in transport protocol. Confounding variables like increased public awareness/education on stroke warning signs and when to call 911 or increasing willingness of centers to do EVT were considered in this study by conducting a step-wise analysis, which associates the results with the time of the protocol change. While this study used data from all the available CSCs, 9 non-stroke centers did not have available data. Additionally, data was not available for EMS dispatch times, number of patients who bypassed non-CSCs, or the number of patients who were taken to a stroke or non-stroke center. As this study was conducted in an urban setting, it may not be generalizable to non-urban settings/geographically distant CSCs, centers that did not undergo the rigorous training on this protocol, or centers with thrombectomy capabilities. This study did not analyze how many stroke mimics were triaged to CSCs, how accurate LVO screening was, or how the protocol worked in hemorrhagic stroke since a diagnosis of AIS was in the inclusion criteria.

Click to read the study in JAMA Neurology

Relevant Reading: The Accuracy of Large Vessel Occlusion Recognition Scales in Telestroke Setting

In-Depth [cross-sectional study]: Patients in Chicago identified as likely having a stroke using the Cincinnati Prehospital Stroke Scale within the last 6 hours were assessed pre-hospital (in EMS transport) for LVO with the 3I-SS, where those with at least a score of 4 were transported to the closest CSC while others were taken to the nearest stroke center. Demographic information on age and sex, medical history, time of symptoms, time of arrival, thrombolytic drug administration, EVT, diagnosis of LVO, and discharge date was collected using the Get With The Guidelines–Stroke program. This study compared EVT rates, stratified by mode of arrival and last known normal time, from 9 months before and after the 3I-SS CSC triage protocol implementation. The 310 pre-implementation and 353 post-implementation eligible patients (68.5±14.9 years, 48.4% men) did not differ on demographic characteristics like age, sex, race, or past medical history. There was also no difference in time from symptom onset to hospital arrival or to time (135.1±53.4 minutes pre-implementation vs 131.4±55.5 minutes post-implementation, P = 0.59) or rates of tissue plasminogen activator administration (n = 124 pre-implementation; n = 136 post-implementation). Rates of discharge to home were similar pre- (35.8%) and post-implementation (38.5%, P = 0.77). The rate of EVT increased 2.8-fold from pre-implementation (4.8%, 95% CI = 3.0%-7.8%) to post-implementation (13.6%, 95%CI = 10.4%-17.6%; P < 0.001). This increase from pre- to post-implementation remained when stratified by mode of arrival (EMS vs walk-in) and last known normal time (<6 vs >6 hours) (4.9%, 95% CI = 4.1%-5.8% vs 7.4%, 95% CI = 7.5%-8.5%; P < 0.001). Importantly, this 2.8-fold increase occurred step-wise around implementation date, with little change in the EVT rates before or after the month of 3I-SS implementation. Post-implementation, compared to pre-implementation, was associated with EVT completion 6 hours after symptom onset (17.0%, 95% CI = 14.4%-20.0% vs 11.2%, 95% CI = 9.6%-14.4%; P = 0.01) but not >6 hours after symptom onset (6.1%, 95% CI = 4.6%-8.2% vs 5.6%, 95% CI = 4.1%-7.7%; P = 0.77). There was not a difference detected in the rate of EVT completion in other transfers like inter-hospital or walk-in, only in transfers by EMS.

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