Clinical Impact of a Local Triage System Using the Emergent Large Vessel Occlusion Screen with a Rotation System of Thrombectomy-Capable Hospitals

Objective: Early intervention with mechanical thrombectomy (MT) is expected to improve the functional outcome in patients with large vessel occlusion (LVO); however, a method for the effective detection of these patients in a prehospital setting and early transport to MT-capable hospitals has not been established. This study aimed to analyze the clinical impact and diagnostic performance of the emergent large vessel occlusion (ELVO) screen and its influence on the transportation time. Methods: The emergency medical services (EMS) in one of the secondary medical areas in Akita, Japan, introduced a prehospital triage system employing an ELVO screen and a rotation system of three MT-capable hospitals on December 1, 2021. Patients who were transferred to each of the three hospitals involved in the rotation system according to a predefined priority list from December 2021 to November 2022 were included in the triage group. Patients who underwent MT in the three hospitals before the introduction of the triage system were assigned to the pre-triage group. We compared the transportation time parameters between the two groups and analyzed the performance of the ELVO screen for the diagnosis of LVOs. This study was approved by the institutional review boards of all three hospitals. Results: Time parameters were compared between the 37 and 42 patients who underwent MT and had detailed data in the triage (n = 351) and pre-triage (n = 43) groups, respectively. The time from door to puncture tended to decrease in the triage group in all hospitals, with one hospital showing a statistically significant shortening of 14 min (p = 0.018). In the triage group, 209 ELVO screen-positive patients were present, with 60 (28.7%) of these having LVO. The sensitivity, specificity, positive and negative predictive values, and area under the curve of the ELVO screen to detect LVO under the present triage system were 87.0%, 47.2%, 28.7%, 93.7%, and 0.671, respectively. Conclusion: The present study demonstrated that the introduction of a triage system may have shortened the time required for MT. ELVO screen may be considered a useful marker for screening LVO in prehospital settings in terms of the sensitivity and negative predictive value; however, further improvement may be necessary to reduce the rate of false positive results.