Impact of Mobile Stroke Units on Patients With Large Vessel Occlusion Acute Ischemic Stroke: A Prespecified BEST-MSU Substudy

BACKGROUND: The impact of mobile stroke units (MSUs) on outcomes in patients with large vessel occlusions eligible for endovascular thrombectomy (EVT) has yet to be characterized. METHODS: We completed a prespecified substudy of patients with EVT-eligible stroke with anterior and posterior circulation large vessel occlusions on computed tomography and/or computed tomography angiography who were enrolled in BEST-MSU (Benefits of Stroke Treatment using a Mobile Stroke Unit). Primary outcome was 90-day utility-weighted modified Rankin scale. Groups were compared using chi-square or Fisher's exact tests for categorical variables, and 2-sample t-tests for continuous variables. Multiple logistic regression was used to assess the effect of MSU on binary outcomes after adjusting for other baseline factors. Results: Of 1515 trial patients, 293 had large vessel occlusions eligible for EVT: 168 in the MSU group and 125 in the emergency medical services group. Baseline characteristics were comparable, with the exception of baseline National Institutes of Health Stroke Scale score (MSU median 19 [interquartile range 13, 23] versus emergency medical services 16 [11, 20], P = 0.002) and study site. The mean (+/- SD) score on the utility-weighted modified Rankin scale at 90 days was 0.63 +/- 0.39 in MSU group and 0.51 +/- 0.41 in emergency medical services group (mean difference 0.13, 95% CI [0.03-0.22]). After adjustment, MSU had significantly higher odds of functional independence (odds ratio 2.60 [95% CI, 1.45-4.77], P = 0.002). Secondary outcomes also favored MSU: early neurologic recovery (30% improvement in National Institutes of Health Stroke Scale score at 24 hours) 68% versus 52%; adjusted odds ratio 1.98 [95% CI, 1.19-3.33]; time of tissue plasminogen activator bolus from symptom onset 65.0 minutes [50.5-92.0] versus 96.0 [79.3-130.0], P <= 0.001. The groups had similar onset to arterial puncture (169.0 minutes [133.5, 210.0] versus 162.0 [135.0-207.0], P = 0.83). Conclusions: In patients with EVT-eligible large vessel occlusion stroke, MSU management was associated with better clinical outcomes compared with standard emergency medical services management. MSU management sped thrombolysis but did not expedite EVT treatment times. Future MSU processes should include efforts to capitalize on the potential of MSUs to provide earlier EVT.