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OPTIMIZATION OF URBAN PREHOSPITAL TRIAGE OF PATIENTS WITH LARGE VESSEL OCCLUSION BY AUSTRIAN PREHOSPITAL STROKE SCALE (APSS)
Background and Aims
The Austrian Prehospital Stroke Scale (APSS) score was developed to predict large vessel occlusion (LVO) and improve prehospital transportation triage. Its accuracy has been previously analyzed retrospectively. We now aimed to investigate the accuracy as well as the impact of the implementation of a triage strategy using this score on treatment times and outcome in a prospective study.
Prospective diagnostic test accuracy and before-after interventional study. EMS prospectively evaluated APSS in patients suspected of stroke. Accuracy was compared to other LVO scores. Patients with APSS ≥ 4 points were brought directly to the comprehensive stroke center. Treatment time frames, neurological and radiological outcome before and after the APSS implementation were compared.
A total of 307 patients with suspected stroke were included from October 2018 to February 2020. Treatable LVO was present in 79 (26%). Sensitivity of APSS to detect those was 90%, specificity 79%, positive predictive value 66%, negative predictive value 95%, area under the curve 0.87 (95%CI 0.83-0.91). This was similar to in-hospital NIHSS (AUC 0.89 95%CI 0.89- 0.92, p=0.06), RACE (AUC 0.88 95%CI 0.87-0.908) and superior to CPSS (AUC 0.83 95%CI 0.78-0.87, p=0.01). Implementation of APSS triage increased direct transportation rate (21% before vs. 52% after; p<0.001) with a significant time benefit (alert to groin puncture time benefit: 51 minutes (95%CI 28-74; p<0.001). Neurological and radiological outcome did not differ significantly.
APSS triage showed an accuracy comparable to in-hospital NIHSS, and lead to a significant optimization of prehospital workflows in patients with potential LVO.