Abstract 3603: Emergency Pre-hospital Stroke Triage In Washington State, Understood Through A Cohort

Abstract

BACKGROUND: Washington State (WA) has legislated an emergency pre-hospital stroke triage system, with 3 levels of self-identified stroke centers. Our objective is to describe the new system using an existing cohort of pre-hospital patients and to extrapolate our findings to all of WA. METHODS: The cohort consisted of a population-based sample of patients whom emergency medical service (EMS) personnel treated over a 30-month period. All patients whose Seattle Fire Department records suggested a possible pre-hospital stroke diagnosis had hospital records reviewed for final diagnosis: TIA, ischemic stroke, intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), or “not a stroke.” These patients were also classified according to the FAST (Face, Arm, Speech, Time last normal) stroke screen. The WA pre-hospital stroke triage tool divides patients into 4 groups: FAST-, FAST+/>6h (arrived at hospital > 6 or unknown hours after last known normal), FAST+/>3.5-6h (arrived in window for intra-arterial (IA) therapies) and FAST+/<=3.5h (arrived in window for IV tPA). RESULTS: The cohort included 1,682 possible stroke patients, mean age 76 years, 60% women. We applied the stroke triage tool to our cohort with results shown in the Table . Assuming similar stroke presentations and given the population of WA is ∼11 times that of Seattle, we estimate that ∼2500 patients/yr would be triaged as possible IV tPA candidates; ∼450 patients/yr would be triaged as possible IA candidates with possibly longer transport to a Level 1 stroke center. There was significant heterogeneity in final diagnoses by triage tool categorization ( Table , P < 0.0005). The triage tool identified combined IV or IA candidates with a sensitivity of 90% (95% CI 83-94%), specificity 91% (90-93%) and C statistic of .90 (.88-.93). Of the 10% of IV or IA candidates missed, 81% had initial NIHSSs < 3. CONCLUSION: These are the first estimates of how the WA pre-hospital stroke triage tool will parse patients. Discrimination of acute ischemic stroke patients eligible for time dependent interventions was excellent; the low NIHSS scores in 81% of those missed suggests an even higher clinically relevant sensitivity. A small proportion (2.4%) of the possible stroke patients presenting to EMS will meet criteria for transport to Level 1 stroke centers, suggesting the additional burden on EMS should be minimal.