Management of Suspected Large Vessel Occlusion with High RACE Score
A patient with a high RACE score (≥5) indicating suspected large vessel occlusion should be transported directly to a comprehensive stroke center capable of endovascular thrombectomy, bypassing primary stroke centers when the additional delay to IV thrombolysis is less than 30 minutes in urban settings or 50 minutes in rural settings. 1, 2
Understanding RACE Score Performance and Triage Decisions
The RACE score ≥5 demonstrates 85% sensitivity for detecting large vessel occlusion (LVO), making it the optimal threshold for prehospital triage decisions 1. However, critical caveats exist:
The positive predictive value is only 50-65%, meaning approximately half of patients triaged as high-risk will not have LVO 1. This is an acceptable trade-off because missing a true LVO (false negative) causes far greater harm than unnecessarily transporting non-LVO patients to comprehensive centers 1.
No LVO prediction scale achieves both high sensitivity and high specificity, with RACE showing moderate discrimination (area under curve 0.72-0.82) 3, 1. The probability of LVO with a negative RACE score can still be ≥10%, so standard stroke protocols must be followed for all suspected stroke patients regardless of score 3, 1.
Transport Strategy Algorithm
Direct transport to comprehensive stroke center ("mothership") is preferred when:
- Transfer time between primary and comprehensive centers is <40 minutes 2
- Additional delay to IV thrombolysis from bypassing the nearest center is <30 minutes in urban settings 2
- Additional delay to IV thrombolysis is <50 minutes in rural settings 2
Drip-and-ship (nearest primary center first) is preferred when:
- Transfer times exceed these thresholds AND the primary center has efficient door-to-needle times 3
- Geography involves large distances between facilities 3
The decision is highly context-specific and depends on: (1) local geography and transport times, (2) door-to-needle efficiency at the primary center, (3) door-in-door-out times for transfers, and (4) door-to-groin-puncture times at the comprehensive center 3.
Confirmation and Treatment Upon Arrival
If the patient arrives at a hospital without CT/MR angiography capabilities:
- Use NIHSS for confirmation—an NIHSS ≥6 provides 87% sensitivity for LVO and should prompt immediate transfer to a comprehensive stroke center 1
- The NIHSS has the largest validation dataset and is already a quality measure, making it the preferred confirmatory tool 1
At the comprehensive stroke center:
- Pre-notification and parallel processing are essential—the stroke team should meet the patient at arrival while simultaneously activating the CT scanner and neuro-interventional team 3
- Administer IV alteplase immediately after hemorrhage is ruled out on non-contrast CT, before obtaining CT angiography 3
- Target door-to-needle time <60 minutes and door-to-groin-puncture time as short as possible 4
- Every 30-minute delay decreases good functional outcome by 8-14% 1
Critical Pitfalls to Avoid
Do not delay transport for extensive on-scene assessment. Once the stroke screen is positive, all actions should focus on moving to the ambulance and beginning transport—IVs and other non-essential treatments can be performed en route 3. Scene time is a controllable variable that cannot be recovered later 3.
Do not assume a low RACE score rules out LVO. Systems using LVO prediction instruments will miss some patients with LVO and milder strokes 3. Clinical judgment must prevail, and patients with any suspected stroke should still be transported urgently to stroke-capable facilities 3.
Do not use rigid protocols without considering local factors. The RACE scale performs similarly to other prehospital LVO scales (CPSSS, LAMS) with no convincing evidence of superiority 1. The choice should depend on local system factors, EMS training, and validated performance metrics in your specific geography 3.
Do not delay IV thrombolysis at comprehensive centers. Under the mothership model, alteplase should be administered before the patient goes to the angiography suite if they arrive within the treatment window 3, 4. The goal is "drip-and-drive" to the angiography suite, not delaying thrombolysis in favor of thrombectomy 3.