Background: Field-based diversion for potential stroke patients who may qualify for endovascular stroke therapy (EST) has been proposed more widely in 2015. In 2015, Kaiser Permanente Northern California (KPNC) redesigned its acute stroke care work flow for all its 21 stroke centers, which included rapid evaluation of all stroke alerts by a stroke neurologist via teleneurology. We investigated the accuracy of EMS-activated stroke alerts.
Methods: From 1/1/16 to 7/10/16, all acute strokes presenting to an ED between 7 AM and midnight were assessed upon arrival by a teleneurologist. We reviewed all telestroke cases to determine the frequency of tPA given, cancelled stroke alerts, and the reasons for not treating with IV t-PA, particularly among ambulance arrivals. Multivariate logistic regression was used to assess age, gender, race, Kaiser membership, and mode of ED arrival as predictors of stroke alert cancellation.
Results: There were 2192 stroke alerts activated. Of these, 1332 (60.7%) arrived by EMS and 860 (39.2%) by non-EMS transport. Of patients arriving by EMS, 651 (48.9%) were cancelled and deemed ineligible for IV t-PA. Most common reasons for cancellation were: last time known well (LTKW) out of range (23%), stroke mimic (33%), symptom resolution (19%), new data regarding goals of care (2%), and other (22.5%). The remaining 681 (51.1%) ambulance arrivals were potential candidates for IV tPA. Subsequently, 334 (50.4%) of them received tPA. Reasons for tPA not given included subsequent resolution of symptoms, concerning CT findings (such as bleed), INR>1.7 in patients on warfarin, further information clarifying time of onset. Among those who arrived by EMS and received IV t-PA, all had CTA and 103 (30.8%) were found to have a large vessel occlusion and 74 (71.8%) underwent EST. In multivariate analysis for all cancelled stroke alerts, arrival by non-EMS transport (OR=1.74, 95% CI 1.44-2.10, p<0.001) was more likely to be cancelled.
Conclusions: Close to half of EMS-activated stroke alerts were cancelled upon initial assessment. Only 5% of patients initially identified by EMS as having a potential acute stroke ultimately underwent EST. Better determination of LTKW and stroke symptoms would improve the accuracy of EMS-initiated stroke alerts.