Prehospital Stroke Identification: Factors Associated with Diagnostic Accuracy.
BACKGROUND
Stroke patients misdiagnosed by emergency medical services (EMS) providers have been shown to receive delayed in-hospital care. We aim at determining the diagnostic accuracy of Fire Department of New York (FDNY) EMS providers for stroke and identifying potential reasons for misdiagnosis.


METHODS
Prehospital care reports of all patients transported by FDNY EMS to 3 hospitals from January 1, 2010, to December 31, 2011, were compared against the American Heart Association Get With The Guidelines (GWTG) database (reference standard) for the diagnosis of stroke. Age-adjusted logistic regression models were generated to explore prehospital patient characteristics which are associated with stroke misdiagnosis.


RESULTS
Of 72,984 patient transports during the study period, 750 had a GWTG diagnosis of stroke, 468 (62%) of which were identified correctly in the field and 282 (38%) were missed. An additional 268 patients were misdiagnosed as stroke when in fact they had an alternative diagnosis. Overall sensitivity was 62.4% (95% confidence interval [CI], 58.9-65.8) and specificity was 99.6% (95% CI, 99.6-99.7). No patients who presented with unilateral weakness, facial weakness, or speech problems were missed, whereas patients with atypical complaints like general malaise, dizziness, and headache were more likely to be missed. Seizures led the EMS providers to both overcall a stroke and miss the diagnosis.


CONCLUSIONS
FDNY EMS care providers missed more than a third of stroke cases. Seizures and other atypical presentations contribute significantly to stroke misdiagnosis in the field. Our findings highlight the need for better prehospital stroke identification methods.