Mobile Stroke Units Associated With Favorable Clinical Outcome In Large Vessel Occlusion Stroke Patients: BEST-MSU Substudy

Introduction: Mobile Stroke Units (MSUs) improve clinical outcome in patients treated with tPA compared to standard management by Emergency Medical Services (EMS), but the impact of MSUs on outcomes in patients with large vessel occlusions (LVOs) having endovascular thrombectomy (EVT) has yet to be determined. Methods: A pre-specified substudy of tPA-eligible stroke patients with LVOs on CT and/or CTA who were enrolled in the Benefits of Stroke Treatment Using a Mobile Stroke Unit (BEST-MSU), a prospective multicenter controlled trial comparing MSU with standard EMS management, was conducted. The primary outcome was the score on the 90-day utility-weighted modified Rankin Scale (uw-mRS). Secondary outcomes were rate of early neurologic recovery (30% improvement in NIHSS score) at 24 hours and functional independence (mRS 0-1) at 90 days. Results: A total of 295 patients were included, 169 in the MSU group and 126 in the EMS group. Baseline characteristics were comparable between the groups, with the exception of baseline NIHSS (MSU median 19.0 [IQR 13.0, 23.0] vs EMS 16.0 [11.0, 20.0], p=0.003). 92% MSU vs 87% EMS LVO patients received tPA, and 78% vs 85% went on to have EVT. MSU LVO patients had faster tPA bolus from symptom onset (65.0 min [50.5, 92.0] vs 96.0 [79.3, 130.0], p<0.001), however the two groups had similar onset to groin puncture (169.0 min [133.8, 212.3] vs 162.0 [135.3, 207.0], p=0.77). The mean (±SD) score on the uw-mRS at 90 days was 0.64±0.39 in the MSU group and 0.50±0.40 in the EMS group (mean difference 0.16, 95% CI [0.07, 0.25] after adjustment for age, baseline NIHSS, premorbid functional status, prior stroke/TIA and site; p<0.001). Early neurologic recovery (68% vs 52%; adjusted OR 1.89 95% CI [1.14,3.17]) and functional independence (Figure 1, 42% vs 29%; 2.48 [1.38,4.55]) also favored the MSU group. Conclusions: In tPA-eligible LVO stroke patients, MSU management was associated with better clinical outcomes compared with standard EMS management.