Effect of Mobile Stroke Unit Dispatch on Process Parameters and Functional Outcomes in Patients With Acute Stroke

BACKGROUND AND OBJECTIVES: Prehospital stroke management on mobile stroke units (MSUs) shortens time to IV thrombolysis (IVT) and improves functional outcomes. Because IVT effects are time-dependent, optimizing workflows and dispatch-related processes may enhance MSU benefits. The B_PROUD-2.0 study aimed to determine the effect of additional MSU dispatch on functional outcomes in acute stroke patients under optimized MSU organization and service delivery. METHODS: In the nonrandomized, controlled B_PROUD-2.0 study (May 2019-April 2021) conducted in Berlin, Germany, MSUs were simultaneously dispatched with conventional care ambulances for suspected stroke emergency calls, whenever available. We compared outcomes and process parameters between dispatch groups (additional MSU dispatch vs conventional care only) among patients with cerebral ischemia with disabling neurologic symptoms and no contraindications to reperfusion treatments. We used data from the Berlin dispatch center and records from the B_SPATIAL registry, consisting of 15 Berlin hospitals with stroke units. We performed pooled analyses with the B_PROUD-1.0 primary population (February 2017-April 2021) and with an extended cohort that also included patients with reperfusion treatment contraindications. The primary and co-primary outcomes were 3-month modified Rankin Scale scores (0: no deficits to 6: death) and 3-tiered disability scale scores. Effect estimates for these outcomes were obtained from ordinal logistic regressions, adjusting for a priori selected covariates after multiple imputation for missing values. RESULTS: Coronavirus disease 2019 pandemic and limited funding hindered full implementation of procedural improvements. A total of 1,050 patients (mean age: 74 years, 46.7% female) were included in B_PROUD-2.0 (vs 1,500 planned). We found no statistically significant effect of MSU dispatch on primary (common odds ratio [cOR] 0.90, 95% CI 0.72-1.14) or co-primary (cOR 0.86, 95% CI 0.63-1.17) outcomes in B_PROUD-2.0, and higher odds of IVT ≤1 hour of dispatch in the MSU group (OR 10.15, 95% CI 7.10-14.51). In pooled B_PROUD-1.0+2.0 primary population analyses (N = 2,666, mean age: 73 years, 46.8% female), we found a beneficial effect on primary (cOR 0.80, 95% CI 0.67-0.96) and co-primary (cOR 0.79, 95% CI 0.64-0.97) outcomes. The average effect on all stroke/TIA patients in the extended cohort (N = 4,336, mean age 75 years, 47.6% female) was also favorable (primary cOR 0.85, 95% CI 0.75-0.95; co-primary cOR 0.86, 95% CI 0.75-0.99). DISCUSSION: While we did not observe statistically significant differences in functional outcomes in the underpowered B_PROUD-2.0 study, we found beneficial effects considering both B_PROUD study periods, also when including all stroke/TIA patients. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov: NCT03931616. Registered: April 26, 2019. First patient enrolled: May 9, 2019. CLASSIFICATION OF EVIDENCE: The B_PROUD-2.0 study provides Class III evidence that the addition of MSUs to conventional care ambulances did not improve functional outcomes at 3 months compared with conventional care ambulances alone in patients with acute ischemic stroke.