Design and validation of prehospital acute stroke triage (PAST) scale to predict large vessel occlusion

Abstract Background and aims Acute ischemic stroke patients with large vessel occlusion (LVO) have severe symptoms and poor prognosis. Early recognition of these patients in prehospital setting contributes to rapid triage to comprehensive stroke centers with endovascular therapy conditions. We aimed to develop a simple and efficient scale to identify LVO and compare with other published scales. Methods Medical records of acute ischemic stroke patients within 24 h of stroke onset at Beijing Tiantan hospital were retrospectively collected. The Prehospital Acute Stroke Triage (PAST) scale was designed based on the National Institutes of Health Stroke Scale (NIHSS) items with higher predictive values for LVO. Receiver operating characteristics curves were used to determine and compare the discriminative ability of each scale. Results A total of 1313 patients diagnosed with acute ischemic stroke were included in this study. Half of the patients were used to design and the other were used to validate the PAST scale. The PAST scale showed a comparable predictive ability to NIHSS to detect LVO (c-statistics, 0.8607 vs 0.8715, p = 0.1889). A FAST scale ≥2 showed a sensitivity of 0.85209, specificity of 0.76301 and accuracy of 0.80518. The PAST scale also showed good performance in subgroup analysis based on the time of onset, infarct location and the type of vascular examination. Conclusions PAST scale is relatively simple and has comparable ability to more complex NIHSS for recognizing large vessel occlusion.