Introduction: Prediction instruments for large vessel occlusion (LVO) have been proposed to identify patients for rapid transport to endovascular thrombectomy (EVT) capable hospitals. This Evidence Review Committee was commissioned by the AHA/ASA 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 using the Quality Assessment of Diagnostic Accuracy (QUADAS)-2 tool.
Results: Thirty-six relevant studies were identified. Most (21/36) recruited patients with confirmed ischemic stroke, with few studies in the pre-hospital setting (4/36) and in populations that included hemorrhagic stroke or stroke mimics (12/36). Most studies had either some risk of bias or unclear risk of bias. Discrimination of LVO, as measured by the c-statistic, mostly ranged from 0.70-0.85. In meta-analysis, no threshold on any instrument predicted LVO with both high sensitivity and specificity (Table). With a positive LVO prediction test, the probability of LVO could be 50% or greater (depending on the LVO prevalence in the population), but the probability of LVO with a negative test could still be 10% or more.
Conclusions: No scale predicted LVO with both high sensitivity and specificity. Systems that use LVO prediction instruments for triage will miss some patients with LVO and milder stroke. More prospective studies are needed in the pre-hospital setting in all patients with suspected stroke, including hemorrhagic stroke and stroke mimics.