Disability outcomes support use of mobile stroke units, despite the cost


By Mardi Chapman

13 Sep 2021

Evidence continues to build for the benefits of mobile stroke units (MSU) but services considering their introduction should first optimise their existing pathways of care, experts say.

According to an editorial in the NEJM, the costs and effort required in implementing a MSU demands “proof that outcomes will be sufficiently better than those associated with existing systems.”

The editorial accompanied publication of the BEST-MSU study which found MSU management of acute ischaemic stroke in patients eligible to receive t-PA results in less disability at 90 days than standard management by emergency medical services (EMS).

The US study, which used an alternating week of care design, also found MSU management resulted in faster and more frequent t-PA treatment compared to EMS.

The prospective study, which enrolled 1,047 patients eligible for t-PA, found the mean score on the utility-weighted modified Rankin scale at 90 day was 0.72±0.35 in the MSU group and 0.66±0.36 in the EMS group.

“The primary analysis that used adjusted logistic regression for dichotomised 90-day scores on the utility-weighted modified Rankin scale of at least 0.91 or less than 0.91 (approximating a score on the modified Rankin scale of ≤1 or >1) resulted in a pooled odds ratio of 2.43 (95% CI, 1.75 to 3.36; P<0.001), favouring MSU in the models with or without inverse-probability weighting,” the study authors said.

In secondary outcomes, the median time from stroke onset to t-PA treatment was 72 minutes in the MSU group compared to 108 minutes in the EMS group.

A third (32.9%) of patients in the MSU group compared to 2.6% in the EMS group were treated within 60 minutes of symptoms onset.

“However, MSU management did not increase the frequency of or expedite EVT, although the time from arrival at an emergency department to the start of EVT was slightly shorter in the MSU group than in the EMS group.”

Worth the expense?

The study investigators said MSUs providing CT scans, point-of-care laboratory testing, and appropriately trained personnel were expensive to implement and maintain.

However they referenced Australian data from the Melbourne Mobile Stroke Unit, which found the service was cost-effective when compared with standard care due to earlier provision of reperfusion therapies.

“Alternatives to MSUs include ambulances that can triage patients through telemedicine but not treat them before arrival at the emergency department; however, an effect of such ambulances on clinical outcomes has not been shown,” the US study said.

The NEJM editorial said independent replication of the BEST-MSU findings was essential given some limitations in the study design, however the findings were consistent with those from a European trial published in JAMA earlier this year.

“After two independent trials, it appears reasonable to conclude that mobile stroke units expedite both assessment and treatment in patients with acute stroke and deliver treatment to more eligible patients, improving average outcomes for patients with a final diagnosis of acute cerebral ischaemia but particularly among those who are eligible for, and who received, thrombolysis,” the editorial said.

“Although stroke-specific emergency medical service vehicles and staff are expensive, the societal and financial burdens that are associated with untreated stroke are sufficient for social pressure to build to introduce mobile stroke units more widely.”

Findings from the BEST-MSU study presented at the International Stroke Conference 2021 earlier this year and an Australian comment on the study by Professor Christoper Bladin have previously been reported in the limbic.

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