Large-Scale Meta-Analysis Further Emphasizes Greater Functional Outcomes With Mobile Stroke Units

Guillaume Turc, MD, PhD

Although the benefits of mobile stroke units (MSUs) have been previously reported, a newly published, large-scale meta-analysis showed that MSU use was associated with a 65% increase in the odds of excellent outcome, a higher proportion of treatment with intravenous thrombolysis (IVT), and a 30-minute reduction in onset-to-IVT times, without safety concerns.

Studies from MEDLINE, Cochrane Library, and Embase from 1960 to 2021 that compared MSU deployment and usual care for patients with suspected stroke were eligible for analysis. Excluding case series and case-control studies, 14 articles met the inclusion criteria. Of these, 4 articles reported results of 3 randomized controlled trials (RCTs), 2 corresponded to large prospective nonrandomized intervention studies with blinded assessment of functional outcome, and 8 to other observational studies.

Led by Guillaume Turc, MD, PhD, professor of neurology, GHU Paris Psychiatrie et Neurosciences, the study used excellent outcome as the primary end point, defined as modified Rankin Scale (mRS) scores of 0 to 1 at 90 days. The risk of bias of individual studies was assessed Turc and another author who did not take part in any included study, using the Cochraine’s Risk of Bias (RoB2) and the Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tools for the RCTs and the nonrandomized studies, respectively.

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Pooling 5 studies (n = 3228), including the notable B_PROUD and BEST-MSU trials (NCT02869386; NCT02190500), the meta-analysis suggested that MSU was superior to usual care regarding excellent outcome in adjusted (pooled odds ratio [OR], 1.64 [95% CI, 1.27-2.13]; P <.001; I2 = 48%) and crude analyses (pooled OR, 1.37 [95% CI, 1.19-1.58]; P <.001; I2 = 0%). Furthermore, the pooled OR for reduced disability was 1.39 (95% CI, 1.14-1.70; P = .001; I2 = 0%) in adjusted analysis (3 studies; n = 1563) and 1.30 (95% CI, 1.14-1.70; P = .001; I2 = 21%) in unadjusted analysis (5 studies; n = 3228).

"The main strength of this review is the use of all published data with consistent findings across studies" Turc et al wrote. "An added strength is the collection of unpublished results from peer-reviewed publications, which allowed us to obtain a more comprehensive and homogeneous analysis of clinically relevant outcomes, disentangle the results of several studies with partially overlapping sets of participants, and conduct adjusted analyses of functional outcome, therefore reducing the risk of confounding."

Seven studies comprising of 4790 patients that reported on IVT distribution showed a pooled crude OR of 1.83 (95% CI, 1.58-2.12; P <.001; I2 = 13%) for MSU vs usual care. Furthermore, investigators found a pooled crude OR of 7.71 (95% CI, 4.17-14.25; P <.001; I2 = 75%) for the proportion of golden-hour thrombolysis among IVT treated patients (8 studies; n = 3351).

Onset-to-IVT time, a critical aspect of efficient stroke care, was reduced by a median of 31 minutes (95% CI, 23-39; P <.001; I2 = 47%) with MSU deployment compared with usual care, with no evidence of publication bias. This analysis included 3322 patients from 13 studies, although even after excluding studies with historical control groups, investigators found similar results. The pooled median reduction in onset-to-IVT time was slightly lower (26 minutes; 95% CI, 16-36; P <.001; I2 = 41%)when considering only the 8 studies focusing on patients with a final diagnosis of acute ischemic stroke.

Five studies that comprised of 671 patients indicated no overall evidence of a significant reduction in onset-to-mechanical thrombectomy time (pooled median difference, 27 minutes; 95% CI, –17 to 71; P = .23; I2 = 86%) when comparing MSU deployment with usual care.

There were no observed differences between treatment groups on all-cause mortality at 7 days (pooled crude OR, 0.74; 95% CI, 0.51-1.09; P = .13; I2 = 33%), however the authors noted significant heterogeneity between population study subgroups. MSU was associated with lower all-cause mortality at 7 days in studies focusing on IVT-treated patients (pooled crude OR, 0.45; 95% CI, 0.27-0.76; I2 = 0%) but not in studies that included patients not treated with IVT (pooled crude OR, 0.97; 95% CI, 0.64-1.45; I2 = 22%)(P for interaction = .01).

All-cause mortality at 90 days, reported in 7 studies comprising 3924 patients, did not differ between treatment groups (pooled crude OR, 0.82; 95% CI, 0.58-1.17; P = .28; I2 = 56%). Additionally, among patients treated with IVT, there were no significant differences in treatment groups in terms of symptomatic intracranial hemorrhage (pooled crude OR, 0.80; 95% CI, 0.52-1.24; P = .32; I2 = 0%).

REFERENCES
1. Turc G, Hadziahmetovic M, Walter S, et al. Comparison of mobile stroke unit with usual care for acute ischemic stroke management: a systematic review and meta-analysis. JAMA Neurol. Published online February 7, 2022. doi:10.1001/jamaneurol.2021.5321.