This is yet another one of those “Get With The Guidelines” stroke analyses, a retrospective dredge with massive imbalances between groups – followed by statistical adjustments capable of turning out whichever result suits an author list with a full, dense printed page of pharma and stroke technology conflicts of interest.
In that respect, the study is unremarkable. Patients with potential stroke who were transported by Mobile Stroke Units were more likely to be functionally independent at baseline and more likely to be transported to a comprehensive stroke center. Thus, patients transported by Mobile Stroke Unit were more likely to be ambulatory and functionally independent at hospital discharge. Everything between the intake and output is just diversions.
Where it becomes further disagreeable is the accompanying editorial, written by two individuals who run Mobile Stroke Unit programs, arguing federal reimbursement ought to cover their pet projects. After a brief brush with the limitations of these data, they assert:
“it convincingly demonstrates through a large, representative, multicenter study that in real-world clinical practice, MSUs are associated with improved short-term patient outcomes”
… quite the over-glamourization of a secondary analysis of quality improvement registry data.
“the magnitude of benefit conferred by MSUs is comparable to that of other widely accepted acute stroke interventions, such as IVT in a 3-hour to 4.5-hour window and specialized stroke units”
… after multiple statistical adjustments of a grossly imbalanced cohort.
“this study demonstrates that MSUs not only benefit patients with AIS eligible for IVT, but also patients with AIS who are ineligible for IVT and patients with other forms of stroke”
… so, even if the MSU – whose mission in life is to provide tip-of-the-spear IVT – doesn’t provide acute treatment, it still confers benefit due to its soothing glow?
“This may be explained by faster imaging and blood pressure control in patients with intracerebral hemorrhage.”
… admission blood pressure for patients with SAH in this cohort was identical between MSU and EMS.
“this study rebuts concerns that by reaching and treating patients with suspected stroke earlier in their clinical course, MSUs could lead to unnecessary IVT treatments and higher rates of hemorrhagic complications. In fact, this study demonstrated the opposite: MSU care was associated with lower rates of stroke mimics”
… yes, as is the typical approach to coding these data, early administration of IVT virtually dictates a patient be coded. Once a patient has received IVT, only strong evidence to the contrary permits consideration of alternative causes of transient neurologic dysfunction – a happy accident also precluding any sICH occurring in “stroke mimics”, because there are none. To wit: only 24 of 4,218 (0.56%) of all MSU responses were “stroke mimics”, whereas 2,114 of 104,466 (2.0%) of all EMS responses were stroke mimics. When all you have is a hammer, everything you see looks like a stroke.
“Furthermore, for the broader population presenting with suspected stroke regardless of final diagnosis, the data suggest the potential for a lower risk of death.”
Again, this is magical thinking. As above, observing benefits outside the scope of the capabilities of an MSU ought prompt reconsideration statistical adjustments rather than plaudits.
These data are simply unsuited to support this sort of unabashed enthusiasm for MSUs. Rather than this editorial supporting their argument to consider funding and reimbursement structures for these tools, their biases shine through to diminish it. Regrettably, as per usual, guidelines and policy will be made by those sponsored to make the most persuasive contortion of data, rather than the most accurate.
“Mobile Stroke Unit Management in Patients With Acute Ischemic Stroke Eligible for Intravenous Thrombolysis”
https://jamanetwork.com/journals/jamaneurology/fullarticle/2824954
“Mobile Stroke Units—Time for Legislation and Remuneration”
https://jamanetwork.com/journals/jamaneurology/fullarticle/2824955