Accuracy of Prediction Instruments for Diagnosing Large Vessel Occlusion in Individuals With Suspected Stroke: A Systematic Review for the 2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke

Abstract

Introduction— Endovascular thrombectomy is a highly efficacious treatment for large vessel occlusion (LVO). LVO prediction instruments, based on stroke signs and symptoms, have been proposed to identify stroke patients with LVO for rapid transport to endovascular thrombectomy–capable hospitals. This evidence review committee was commissioned by the American Heart Association/American Stroke Association to systematically review evidence for the accuracy of LVO prediction instruments. Methods— Medline, Embase, and Cochrane databases were searched on October 27, 2016. Study quality was assessed with the Quality Assessment of Diagnostic Accuracy-2 tool. Results— Thirty-six relevant studies were identified. Most studies (21 of 36) recruited patients with ischemic stroke, with few studies in the prehospital setting (4 of 36) and in populations that included hemorrhagic stroke or stroke mimics (12 of 36). The most frequently studied prediction instrument was the National Institutes of Health Stroke Scale. Most studies had either some risk of bias or unclear risk of bias. Reported discrimination of LVO mostly ranged from 0.70 to 0.85, as measured by the C statistic. In meta-analysis, sensitivity was as high as 87% and specificity was as high as 90%, but no threshold on any instruments predicted LVO with both high sensitivity and specificity. With a positive LVO prediction test, the probability of LVO could be 50% to 60% (depending on the LVO prevalence in the population), but the probability of LVO with a negative test could still be ≥10%. Conclusions— No scale predicted LVO with both high sensitivity and high specificity. Systems that use LVO prediction instruments for triage will miss some patients with LVO and milder stroke. More prospective studies are needed to assess the accuracy of LVO prediction instruments in the prehospital setting in all patients with suspected stroke, including patients with hemorrhagic stroke and stroke mimics.

The Speech Arm Vision Eyes (SAVE) scale predicts large vessel occlusion stroke as well as more complicated scales

“…However our study included extracranial internal carotid LVOs and provided 95% CIs not included in the original FAST-ED study 7. The NIHSS remains a key feature of acute stroke assessments, but it is considered too long and complex for prehospital use 2. It is not yet clear whether this also applies to the mNIHSS, though this scale is longer than most dedicated LVO prediction scales.…”

“…Earlier prediction of whether or not a patient has a LVO could assist with time-sensitive prehospital and emergency department (ED) decisions aimed at decreasing EVT treatment times 2. LVO prediction scales use clinical information to attempt to make this distinction before vessel imaging.…”

“…However, none are considered to be more accurate than the others 2. There remains a need for a scale that is short, easy to score, and captures cortical or hemispheric deficits that are highly predictive of LVO stroke.…”

AHA/ASA 2018 AIS guidelines: impact and opportunity for endovascular stroke care

“…Of particular relevance to NeuroInterventionalists was “Accuracy of Prediction Instruments for Diagnosing Large Vessel Occlusion in Individuals with Suspected Stroke: A Systematic Review for the 2018 Guidelines for the Early Management of Patients with Acute Ischemic Stroke’ 14. This independent review determined that no dominant pre-hospital stroke clinical evaluation tool exists that would lead to a recommendation of one pre-hospital stroke severity scale above another.…”

“…What field score should be utilized? The independent review board that was part of the AHA/ASA Guidelines Committee determined that the performance of the various scales is similar 14. Should the Society take a position on one score above another, to guide groups currently thinking about options for this?…”