Diagnostic Test Accuracy Protocol
Worldwide, stroke is the leading cause of death. By 2020, 19 million out of 25 million annual stroke deaths will occur in developing countries. Some 88% of these events are ischemic strokes, with the remainder being hemorrhagic strokes. Stroke is also the leading cause of disability with 30% of stroke survivors requiring life-long assistance with their activities of daily living, 20% requiring assistance with ambulation, and 16% requiring institutional levels of care. The underlying process of ischemic stroke is thrombi. Thrombi are made up of fibrin, among other components. The fibrin component is the substrate of a medication, tissue plasminogen activator (tPA), which works to dissolve the thrombus, thereby restoring blood flow through the previously obstructed vessel. Failure to restore blood flow in a timely fashion results in an ischemic stroke, infarction of brain tissue. Transient ischemic attacks (TIAs) are prognosticators for future strokes and also require rapid identification so that physicians can confirm whether or not the symptoms have resolved and then work towards early risk stratification, which has been shown to decrease recurrence. The gold standard for diagnosis of strokes and TIAs is the evaluation by a neurologist upon review of history, physical and a non-contrast brain computed tomography (CT) scan. Intravenous-tPA is the only approved treatment of acute ischemic stroke. However, utilization of intravenous-tPA is limited by its time sensitivity, and this medication can only be provided to patients within a window of 0 to 4.5 hours after the onset of symptoms. An ideal system for rapid thrombolytic delivery begins with rapid and accurate stroke detection at the time of first contact with medical personnel. Stroke pathways that include prehospital notification have been demonstrated to reduce door-to-treatment time and improve outcomes in patients. A number of prehospital stroke scales have been designed to aid in the early identification of potential stroke by paramedics in the field. There is a paucity of head-to-head trials of the currently validated stroke scales and there is no meta-analysis that examines the existing scales and their screening accuracy. These scales are all used in the prehospital or emergency department setting but do not replace the information gathered from the history and physical examination by an attending physician. They are not for use by neurologists but for prehospital stroke staff and, in some studies, for emergency physicians (which this review will explore). Furthermore, hemorrhagic strokes require rapid assessment, and it is believed that early identification and intervention is associated with signals toward decreased end volume size of hemorrhage.