RACE stands for Rapid Arterial Occlusion Evaluation. The RACE scale was designed in 2011 by a group of neurologists from Hospital Germans Trias i Pujol with the aim of providing a prehospital scale the could identify patients with acute stroke due to large vessel occlusion, possible candidates for intravascular treatment. The RACE scale was designed based on the NIHSS scale, selecting the items that were most frequently associated with arterial occlusion, according to the results of an retrospective study of more of 600 patients with ischemic stroke and mix to the stroke unit of Hospital Germans Trias i Pujol in Badalona, Barcelona. The race scale evaluates five items, facial weakness, arm weakness, leg weakness, head and gaze deviation, and aphasia and agnosia, and gives a total score between zero and nine. Neurological scales allow us to describe the clinical situation and monitor patients' progress. The NIHSS scale is used in the in-hospital setting, especially in stroke units and evaluates 15 items. It has a certain degree of complexity and its application in the prehospital setting is difficult. In contrast, the RACE scale is a simpler, faster tool making it easy to use by emergency medical professionals. The table shows the equivalent scoring on the RACE scale and the NIHSS scale. First, facial weakness is evaluated with a score of between zero and two, depending on the degree of asymmetry. Then, arm weakness is assessed. The patient is instructed to keep their arm raised for ten seconds. The patients score 0 if they can keep their arm raise for ten seconds. 1 if they can raise it but it drops to the bed again within ten seconds and 2, if they cannot raise their arm. Leg weakness is assessed in a similar way, keeping the leg raised for five seconds and scoring in the same way as the arms. The fourth item assesses head and gaze deviation present in patients with severe stroke, deviating towards the opposite side from the motor deficit. Finally, if there's a left-sided weakness, agnosia is assessed. The patient is asked if they recognize their left arm, and if they think that they can move it properly. If there's right-sided weakness, then the patient is assessed for aphasia by assessing if the patient can understand and obey two simple commands, close your eyes, and make a fist. The time needed for evaluation using the RACE scale is under two minutes. The RACE scale was validated in North Barcelona and Maresme area between 2011 and 2013. The results were published in the journal Stroke in 2014. For the validation study, a working group was created with two neurologists from Hospital Germans Trias i Pujol and two EMS nurses. An in-person training program was conducted, aimed at ambulance technicians from the local ambulance service, Groupa Lapo, in this particular area in the north of Barcelona. Following this a perspective registry was started of all patients transferred to the Hospital Germans Trias I Pujol by basic life support ambulance as part of stroke code. The RACE score obtained by EMS technicians at the pre-hospital level was entered into a database along with other critical variables. As the baseline, NIHSS scale performed by the neurologist and the presence of large vessel occlusion. A total of 357 patients were registered over two years. First of all, we can see that the RACE scale correlates well with the NIHSS scale. That is, the RACE scale preformed in the pre-hospital setting coincides with the NIHSS that were used in the hospital setting. This shows that patients with a low RACE score also have a low NIHSS score and conversely, those with a high RACE score have a high NIHSS score. On the horizontal axis, we can see the scores from the RACE scale, and on the vertical axis the NIHSS scale. For example, if a patient scores two on the RACE scale this corresponds to a score of less than ten on the NIHSS, which would be a mild stroke. In contrast, for a RACE score of 8 the NIHSS score would be between 10 and 20, representing severe stroke. Regarding the presence of large vessel occlusion, we can see that the RACE score was significantly higher in patients with ischemic stroke with arterial occlusion, mean score of 6. Then patients with an ischemic stroke without occlusion, mean score of 3. The study assessed the predictive power of the different cutoff points on the RACE scale for detecting large vessel occlusion. The higher the score on the RACE scale and therefore the more severe the stroke, the lower the sensitivity and greater the specificity for detecting large vessel occlusions. The ideal cut-off point for detecting arterial occlusion was deemed to be a RACE score of five or more. In the graph below, patients with stroke due to large vessels occlusion are shown in red and patients with other diagnosis, ischemic stroke without large vessel occlusions, hemorrhagic stroke, or stroke mimics, are shown in blue. If we take a cut-off point of five or more points on the RACE scale, we can identify most of the patients with a large vessel occlusions, including few patients with other diagnoses. Thus, the RACE scale has a sensitivity of 5% and a specificity of 68% for detecting patients with arterial occlusion. The most common diagnosis in patients with a RACE score of five or more was ischemic stroke with ulterior occlusion in 61%, followed by hemorrhagic stroke in 20%, ischemic stroke with occlusion in 16%, and stroke mimics in 3. In summary, the RACE scale is a valid tool that allows us to detect patients with a higher likelihood of having large vessel occlusions, who are potential candidates for endovascular treatment.