Researchers from the University of Tennessee Health Science Center were part of a multisite study that found that early intervention by mobile stroke units (MSUs) improves outcomes for stroke patients. The study results were published today in The New England Journal of Medicine.
The UTHSC Mobile Stroke Unit was a participating site in the trial under the leadership of College of Nursing Professor Anne Alexandrov, PhD, RN, AGACNP-BC, ANVP-BC, NVRN-BC, CCRN, FAAN, and UTHSC Neurology Chair and Professor Andrei Alexandrov, MD.
A mobile stroke unit is an ambulance with a CT scanner that enables faster treatment with the clot-busting drug, tissue plasminogen activator (tPA), than standard transport by emergency medical services (EMS) ambulances to hospitals for tPA treatment. The tPA treatment breaks down clots in the brain’s arteries that cause ischemic stroke; this results in improved blood flow to the brain. The multicenter, controlled trial enrolled 1,515 patients in seven cities over six years and was funded by the Patient Centered Outcomes Research Institute (PCORI).
The study compared MSU tPA treatment to standard EMS transport and hospital-based tPA treatment for patients within 4.5 hours of stroke symptom onset. The primary comparison was between the patients who received tPA in both groups. Of the 1,047 patients eligible for tPA, 617 received care by an MSU and 430 by EMS.
Study results showed that patients who were treated in MSUs fared significantly better than those transported by EMS to hospitals for care. For MSU patients, 55% were functionally independent 90 days after the stroke. For EMS-managed patients, fewer (44.4%) were functionally independent 90 days after the stroke. Additionally, fewer patients managed on MSUs died from severe stroke symptoms within three months of enrollment compared to those transported by EMS.
The median time from stroke onset to the tPA treatment was much shorter for the MSU group since patients were able to be treated before reaching the hospital. MSU patients received tPA treatment within 72 minutes of symptom onset, but the median time for EMS patients to receive tPA treatment in the hospital was 108 minutes.
Previous trials have shown that the benefit of tPA is greater when it occurs within the first hour following stroke. “We know that almost two million neurons die every minute that treatment is delayed, so being treated significantly faster on an MSU is important to reduce the brain injury caused by stroke,” said Dr. Anne Alexandrov.
In this study only 2.6% of patients in the EMS group received tPA within the first hour of stroke symptom onset, whereas 32.9% of patients in the MSU group received it in the first hour.
UTHSC launched its Mobile Stroke Unit in 2016. Currently, the UTHSC MSU is not in service, as improved reimbursement is being negotiated with the Centers for Medicare and Medicaid to cover MSU operational expenses for the specialized services offered on mobile stroke units.
The Drs. Alexandrov are collaborating with other MSUs and state and national legislators to improve reimbursement for MSU services. They hope that this important study could be a factor that leads to improved MSU reimbursement that is so desperately needed for these programs around the country to remain viable. Presently, all MSUs in the world rely on donors to support their operational costs.
While this is the first multisite clinical trial in the United States demonstrating the effectiveness of MSUs at increasing the number of patients who are functionally independent after stroke, it is the second study worldwide documenting these outcomes, said Dr. Anne Alexandrov, who is recognized as the leading international nursing expert in acute stroke management.