Clinical predictors of accurate prehospital stroke recognition.

BACKGROUND AND PURPOSE: Prehospital activation of in-hospital stroke response hastens treatment but depends on accurate emergency medical services (EMS) stroke recognition. We sought to measure EMS stroke recognition accuracy and identify clinical factors associated with correct stroke identification. METHODS: Using EMS and hospital records, we assembled a cohort of EMS-transported suspect, confirmed, or missed ischemic stroke or transient ischemic attack cases. The sensitivity and positive predictive value (PPV) for EMS stroke recognition were calculated using the hospital discharge diagnosis as the gold standard. We used multivariable logistic regression analysis to determine the association between Cincinnati Prehospital Stroke Scale use and EMS stroke recognition. RESULTS: During a 12-month period, 441 EMS-transported patients were enrolled; of which, 371 (84.1%) were EMS-suspected strokes and 70 (15.9%) were EMS-missed strokes. Overall, 264 cases (59.9%) were confirmed as either ischemic stroke (n=186) or transient ischemic attack (n=78). The sensitivity of EMS stroke recognition was 73.5% (95% confidence interval, 67.7-78.7), and PPV was 52.3% (95% confidence interval, 47.1-57.5). Sensitivity (84.7% versus 30.9%; P<0.0001) and PPV (56.2% versus 30.4%; P=0.0004) were higher among cases with Cincinnati Prehospital Stroke Scale documentation. In multivariate analysis, Cincinnati Prehospital Stroke Scale documentation was independently associated with EMS sensitivity (odds ratio, 12.0; 95% confidence interval, 5.7-25.5) and PPV (odds ratio, 2.5; 95% confidence interval, 1.3-4.7). CONCLUSIONS: EMS providers recognized 3 quarters of the patients with ischemic stroke and transient ischemic attack; however, half of EMS-suspected strokes were false positives. Documentation of a Cincinnati Prehospital Stroke Scale was associated with higher EMS stroke recognition sensitivity and PPV.