What is the management approach for a patient with a suspected large vessel occlusion stroke and a high RACE (Rapid Arterial oCclusion Evaluation) score?

Management of Suspected Large Vessel Occlusion Stroke with High RACE Score

A patient with suspected large vessel occlusion (LVO) stroke and a high RACE score (≥5) should be transported directly to a comprehensive stroke center capable of endovascular thrombectomy, as this threshold demonstrates 85% sensitivity for detecting LVO and represents the optimal balance for prehospital triage decisions. 1

Understanding the RACE Score Performance

The RACE (Rapid Arterial oCclusion Evaluation) scale was specifically designed and validated for prehospital LVO detection by emergency medical services personnel. 2 The scale consists of 5 items: facial palsy (0-2 points), arm motor function (0-2), leg motor function (0-2), gaze deviation (0-1), and aphasia or agnosia (0-2), with scores ranging from 0-9. 2

Key Performance Characteristics at RACE ≥5:

• Sensitivity: 66-85% for detecting LVO 3, 2
• Specificity: 68-72% 3, 2
• Positive predictive value: 29-42% 3, 2
• Negative predictive value: 93-94% 3, 2

The moderate positive predictive value means that 50-65% of patients with RACE ≥5 will be false positives for LVO. 1 However, this is an acceptable trade-off in stroke systems of care, as the harm of missing an LVO (false negative) far outweighs the cost of transferring patients who don't have LVO. 1

Clinical Decision Algorithm

For Prehospital/EMS Setting:

When RACE score ≥5 is identified:

1. Activate direct transport to comprehensive stroke center with endovascular thrombectomy capability, bypassing primary stroke centers if necessary 4, 2

2. Pre-notify the receiving facility to prepare the thrombectomy team 2

3. Consider helicopter air ambulance for remote/rural areas to minimize time to comprehensive stroke center 4

4. Document last known well time as this is critical for treatment eligibility 3

Important Context on False Positives:

Even when RACE ≥5 patients don't have LVO on imaging (61% false positive rate), the majority still benefit from comprehensive stroke center care: 4

• 20.6% have non-LVO ischemic strokes requiring advanced care 4
• 16.1% have intracranial hemorrhages 4
• 5.9% have other neurologic conditions requiring CSC capabilities 4
• Overall, 46.4% require neurologic intervention at a comprehensive center 4

For Emergency Department Setting Without Advanced Imaging:

If the patient arrives at a hospital without CT angiography or MR angiography capabilities and has RACE ≥5, the NIHSS should be used for confirmation, as it has the largest validation dataset and is already a quality measure. 1 An NIHSS ≥6 provides 87% sensitivity for LVO and should prompt immediate transfer to a comprehensive stroke center. 1

Critical Caveats and Pitfalls

No LVO prediction scale achieves both high sensitivity and high specificity. 1 The RACE scale shows moderate discrimination with area under the curve of 0.72-0.82, meaning it's good but not perfect. 1, 3, 2

A negative RACE score (<5) does not rule out LVO. The probability of LVO with a negative test can still be ≥10%. 1 Therefore, clinical judgment and standard stroke protocols must still be followed for all suspected stroke patients regardless of RACE score.

Performance may vary by setting. The RACE scale demonstrated lower sensitivity (66%) and positive predictive value (29%) in U.S. suburban/rural EMS settings compared to the original Spanish validation study. 3 This highlights the importance of local validation and ongoing quality assessment.

The RACE scale performs similarly to other prehospital LVO scales (CPSSS, LAMS), with no convincing evidence for superiority of any single instrument. 1 The choice should depend on local system factors and EMS training.

Treatment Priorities Upon Arrival

Once at a comprehensive stroke center with RACE ≥5:

• Immediate CT/CTA imaging to confirm LVO 2
• Simultaneous preparation for IV thrombolysis if within time window and no contraindications 5
• Thrombectomy team activation for confirmed LVO 5
• Every 30-minute delay decreases good functional outcome by 8-14%, making speed essential 5

The posttest probability of LVO with a positive RACE ≥5 ranges from 35-50% depending on the underlying prevalence in your population, but this is sufficient to justify direct transport to comprehensive stroke centers given the time-sensitive nature of thrombectomy. 1