Can non-contrast head CT and stroke severity be used for stroke triage? A population-based study

Background and Purpose: Acute ischemic stroke (AIS) patients may benefit from endovascular thrombectomy (EVT) up to 24 h since last known normal (LKN). Advanced imaging is required for patient selection. Small or rural hospitals may not have sufficient CT technician and radiology support to rapidly acquire and interpret images. We estimated transfer rates using non-contrast head CT and stroke severity to select patients to be transferred to larger centers for evaluation. Methods: We identified all AIS among residents of the study region in 2010. Only cases age ≥ 18 with baseline mRS 0–2 that presented to an ED were included. Among cases that presented between 6 and 24 h from LKN, those without evidence of acute infarct on head CT and with initial NIHSS ≥6 or ≥ 10 were identified. Results: Of 1359 AIS cases, 448 (33.0%) presented between 6 and 24 h, of which 383 (85.5%) showed no evidence of acute infarct on CT. Of cases with no acute infarct on CT, 89/383 (23.2%) had NIHSS ≥6, of which 66 (74.2%) initially presented to a hospital without thrombectomy capabilities; and 51/383 (13.3%) had NIHSS ≥10, of which 40 (78.4%) presented to a non-thrombectomy hospital. Conclusions: In our population, 40–66 AIS patients annually (0.8–1.3/week, or 3–5 patients/100,000 persons/year) may present to non-thrombectomy hospitals and need to be transferred using non-contrast CT and stroke severity as screening tools. Such an approach may sufficiently mitigate the impact of delays in treatment on outcomes, without overburdening the referring nor accepting hospitals.