Mobile Stroke Units in Berlin Led to Faster Care, Better Outcomes

LOS ANGELES, CA—Deploying mobile stroke units on the streets of Berlin, Germany, not only got thrombolytic therapy to patients with acute cerebral ischemia faster, but also improved functional outcomes 3 months after the event, results of the B_PROUD trial show.

Patients treated when a specialized unit—called a STEMO—was available were more likely to receive thrombolytic therapy (60% vs 48%) and had a shorter time to treatment (50 vs 70 min; P < 0.01 for both), Heinrich Audebert, MD (Center for Stroke Research Berlin), reported at the International Stroke Conference here.

These patients also had a positive shift in modified Rankin Scale (mRS) scores at 3 months (P < 0.001). An mRS score of 0 to 2, which indicates functional independence, was seen in 63% of patients treated when a STEMO was available and 57% of those treated at other times.

The study is “the first proof that prehospital treatment actually leads to better outcomes, and this will surely help us to continue with these services in different areas,” Audebert told TCTMD. “If we have an effective therapy, we can’t wait until the patient comes to our hospital. We really need to go out for the patient and try to offer this treatment at the scene.”

In my opinion, it’s the speed of getting the appropriate treatment to the patient. That is what the mobile stroke unit provides. James Grotta

Asked to comment on the study, James Grotta, MD (Memorial Hermann – Texas Medical Center, Houston), said, “It’s huge.” Grotta was instrumental in bringing the first mobile stroke unit to the United States about 6 years ago and is currently heading the ongoing BEST-MSU study to evaluate the clinical impact, as well as the cost-effectiveness, of these units.

“If our study corroborates this study, there’s no excuse for a city not to have a mobile stroke unit,” Grotta told TCTMD, adding that any city or metropolitan area with a population of about 350,000 or more could justify the expense. “If we’re able to confirm that they are effective and can show cost-effectiveness and over the next few years [get] better reimbursement, I think 10 years from now every significant population area will have them.”

B_PROUD

It’s well known that the benefits of thrombolysis for acute ischemic stroke are enhanced with speedier treatment. German investigators came up with the idea of using mobile stroke units equipped with CT to allow for initiation of thrombolytic therapy before patients reached the hospital.

Prior studies have confirmed that the strategy does, in fact, lead to more rapid treatment, but an effect on patient outcomes had been more elusive.

In the B_PROUD trial, Audebert and his colleagues examined the clinical impact by using random allocation of patients based on the availability of three STEMO units in Berlin, which were on the roads from 7 am to 11 pm. The trial included patients who had an onset-to-alarm time that did not exceed 4 hours, a final diagnosis of ischemic stroke/TIA, and no absolute contraindications to thrombolysis or thrombectomy: 794 patients were treated when the STEMO was available to respond and 749 were treated when a specialized unit was not available. In the former group, 74% of patients were actually treated on the mobile stroke unit; for the remaining 26%, primary emergency medical services personnel canceled deployment before STEMO arrival.

Patients in the STEMO-available group were more likely to receive thrombolytic therapy, with a shorter time to treatment, and were more likely to be treated within 60 minutes (13% vs 4%; P < 0.01).

The primary outcome, a shift analysis looking across the range of mRS scores at 3 months, favored the patients treated when a STEMO was available (OR 0.74; 95% CI 0.60-0.90).

During the trial, the investigators introduced a co-primary outcome that divided mRS scores into three groups—0 to 3 or living at home, 4 to 5 or in nursing care, and 6 (death)—“as we felt that we would not get modified Rankin Scale information in all our patients,” Audebert said. An analysis of this endpoint provided similar results but fell shy of statistical significance (OR 0.75; 95% CI 0.56-1.01).

There were no significant differences between groups in terms of symptomatic hemorrhage, death within 7 days, or discharge home. Quality of life according to the European Quality of Life – 5 Dimensions (EQ-5D) total score at 3 months was significantly higher in patients treated when a STEMO was available (P = 0.004).

‘A Really Important Step’

Although quicker and more frequent use of thrombolytic therapy explains most of the beneficial effects seen in the study, it’s possible that the specialized units also helped by providing earlier neurological assessment, with continuous monitoring and complication management in the prehospital setting, Audebert noted. Also, there was a second medical assessment when the patient arrived at the hospital.

Grotta agreed that there could be other factors at play when it comes to the positive effects associated with mobile stroke units, including earlier examination by a physician, maintenance of stable blood pressure, and early detection of neurological deterioration. Also, he said, use of mobile stroke units speeds delivery of endovascular therapy once patients arrive at the hospital, although that was not demonstrated in B_PROUD. “In my opinion, it’s the speed of getting the appropriate treatment to the patient. That is what the mobile stroke unit provides,” Grotta said.

The benefits seen in B_PROUD are even more impressive because the study was set up in a way that would be expected to dilute any positive effects, said Grotta. Patients were included in the STEMO-available group even if they weren’t picked up by the mobile stroke unit and even if they didn’t receive thrombolytic therapy, he noted. “Considering the fact that so many patients didn’t get tPA, the fact that they were able to discover a treatment effect, I think is remarkable.”

The BEST-MSU study in the United States maintains more of a focus on patients who are eligible for thrombolytic therapy as determined by a blinded adjudicator. It also prospectively collects information on how much it costs to run a mobile stroke unit and how much money—if any—is saved downstream.

The financial aspect is important, Grotta noted, because mobile stroke units in the US are mainly paid for through philanthropic funds and reimbursements for their use currently cover only about half of the cost of running the units. Studies like B_PROUD and BEST-MSU are needed to convince payers to reimburse at a higher level, he added.

In that context, Grotta said, Audebert’s presentation today “is a really important step.”