In a time where more than half of all patients with acute stroke and most patients with severe stroke arrive at the hospital via emergency medical services, a study suggests mobile stroke units are better equipped to accurately triage patients.
Stefan A. Helwig
New results of a randomized multicenter trial suggest that mobile stroke unit-based management— deployed with a paramedic, stroke physician, and radiologist, with further consultation available by telemedicine—allowed for 100% accuracy in triage decisions, outperforming Los Angeles Motor Scale (LAMS) prehospital management, which allowed for 70% of triage decisions to be accurate.1
In order to explore how optimized prehospital management based on the use of the LAMS compares with management in a mobile stroke unit in accurately triaging patients to the appropriate hospital with or without interventional treatment—either a comprehensive or primary stroke center, respectively. The trial included a 3-month follow-up and 116 adult patients with stroke.
“Depending on the specific health care environment considered, both approaches are potentially valuable in triaging stroke patients,” study author Stefan A. Helwig, medical assistant, neurology, Saarland University Hospital, and colleagues wrote. “Transferring patients with large-vessel occlusion or intracranial hemorrhage to hospitals without interventional treatment options is an unresolved medical problem that is most pronounced in rural areas. The resulting secondary interhospital transfers cause considerable costs and detrimental delays before treatment.”
Helwig and colleagues did acknowledge the limitations of the work, noting that some mobile stroke programs do not use vascular imaging, despite the presence of CT scanners in many units. Additionally, although it may require a higher level of radiological competence among staff, it does not cause delays longer than 5 minutes. Additionally, they acknowledged their exclusion of 106 and 96 patients in the mobile and LAMS groups, respectively, due to a lack of vascular imaging.
In total, the LAMS group included 53 patients (mean age, 74 years) and the mobile stroke unit group included 63 (mean age, 75 years). Accurate triage decision was achieved for 37 of the 53 patients in the LAMS group and for all 63 in the mobile group, for a difference of 302% (95% CI, 17.8-42.5; P <.001).
In the LAMS group, of the patients with large-vessel occlusion or intracranial hemorrhage (n = 17), 41.2% required secondary transfers, compared to 0% (difference, 41.2%; 95% CI, 17.8—64.6; P = .02) of those patients with these conditions in the mobile stroke unit group (n = 11). Ultimately, the LAMS-optimized prehospital management provided the appropriate level of care with 35.3% sensitivity, 86.1% specificity, 54.5% positive predictive value, and 73.8% negative predictive value.
The LAMS at a cut point of ≥4 led to an accurate diagnosis of LVO or ICH for 76.5% (13 of 17 patients; 6 triaged to a comprehensive center) and of LVO alone for 77.8% (7 of 9 patients; 2 triaged to a comprehensive center). Additionally, stroke management metrics were better in the mobile stroke group, but patient outcomes were not significantly different.
In an accompanying editorial, Jason McMullan, MD, MS, and Pooja Khatri, MD, MSc, of the departments of emergency medicine and neurology, respectively, at the University of Cincinnati, noted that this study “establishes an important foundation of evidence.”2
They wrote that in a time where more than half of all patients with acute stroke and most patients with severe stroke arrive at the hospital via emergency medical services, accurate triage is essential—especially now when prehospital identification of stroke and the ensuing triage is no longer as simple as decades ago.
“As new treatment options have been established (e.g., endovascular therapy) and patient selection has expanded, prehospital tools must also evolve,” the pair wrote. Although McMullan and Khartri lauded the mobile stroke unit for its reliable and rapid ability to collect vascular imaging, they detailed that “even if mobile stroke units are consistently 100% accurate, worldwide integration of mobile stroke units into stroke systems of care is not feasible.”
They argued that the role of clinical decision-making will always be present, and judgment will always be flawed, so prioritization of what is considered acceptable must be defined.
“Trauma systems accept a 40% over-triage rate, choosing sensitivity over specificity; this rate may be unacceptable to busy comprehensive stroke centers,” they wrote. “The 77% sensitivity and 81% specificity of a nonmodified LAMS seem reasonable as a tool to preferentially triage patients to a comprehensive stroke center.”
1. Helwig SA, Ragoschke-Schumm A, Schwindling L, et al. Prehospital stroke management optimized by use of clinical scoring vs mobile stroke unit for triage of patients with stroke: A randomized clinical trial. JAMA Neurol. Published online September 3, 2019. doi:10.1001/jamaneurol.2019.2829.
2. McMullan J, Khatri P. Getting the right patient to the right place in the right amount of time—a role for both mobile stroke units and prehospital clinical scales. JAMA Neurol. Published online September 3, 2019. doi:10.1001/jamaneurol.2019.2839.