NEW YORK (360Dx) – A two-year-pilot program underway in Alberta, Canada is seeking to cut the time to deliver stroke therapy services to rural patients through a mobile unit equipped with point-of-care diagnostics.
Alberta's stroke ambulance, run by Alberta Health Services, is particularly focused on identifying and treating ischemic strokes, or strokes caused by blood clots, which are responsible for about 80 percent of strokes, according to according to Anna Füzéry, a clinical biochemist with Alberta Health Services who is medical/scientific lead of Edmonton's citywide point-of-care testing program. The preferred treatment for ischemic strokes, thrombolysis, involves using tissue plasminogen activator (tPA) to breakdown clots, but tPA has been shown to be most effective if administered within three hours of the stroke having occurred, she said.
"Early intervention is key to stroke management. The problem with this therapy is that before you can administer it to a patient, you have to first exclude certain contraindications," Füzéry said during a presentation at the American Association of Clinical Chemistry Point of Care Testing Symposium in Washington, DC last week.
To diagnose ischemic stroke and determine whether a patient is a candidate for thrombolysis treatment, the mobile team in Alberta's stroke ambulance must exclude hemorrhagic stroke, caused by a burst blood vessel, and coagulopathies, or bleeding disorders in which the blood's ability to form clots is impaired, prior to administering treatment.
To make those diagnoses, the stroke ambulance includes a CT scanner, which is reviewed remotely by a neurologist on call at University of Alberta Hospital in Edmonton. In addition, the stroke ambulance includes a Roche Accu-Chek Performa glucose meter to rule out hypo- and hyperglycemia, which can mimic the symptoms of a stroke; a Roche CoaguChek XS Pro INR meter to check anticoagulation status prior to treatment; and a Sysmex pocH-100i hematology analyzer to rule out thrombocytopenia, or low platelet count, prior to treatment.
The stroke ambulance was launched to address the fact that 17 percent of Alberta's population of 3.5 million live in rural areas, where many local hospitals do not have stroke services. There are an estimated 6,500 new strokes a year in Alberta and the province spends an estimated $200 million to $300 million (in US dollars) per year on stroke care, primarily associated with the long-term consequences of strokes, according to Füzéry.
"The problem for Alberta, and especially the 17 percent of the population that lives in rural areas, is that this treatment was only available at primary and comprehensive stroke centers until the stroke ambulance was put into service," Füzéry said.
Patients suspected of suffering from strokes at rural hospitals where thrombolysis was not available were often transported to the University of Alberta Hospital in Edmonton. The hospital serves a catchment area with a 155 mile radius, which means that transportation time could significantly cut into the three-hour window in which tPA should be administered following a stroke, Füzéry said.
With the stroke ambulance pilot program, when a patient at a rural hospital is suspected of suffering from a stroke, the patient is put into a regular ambulance headed toward Edmonton, and the stroke ambulance is dispatched from Edmonton to meet the regular ambulance at a coordinated halfway point. Once the patient is transferred from the regular ambulance to the stroke ambulance at the meeting spot, the assessment begins immediately, according to Füzéry.
The stroke ambulance includes a hydraulic leveling system, to ensure that the CT scanner and the point-of-care devices can function regardless of the terrain in which the stroke ambulance is traveling, Füzéry said. The van is staffed by one CT technologist, two paramedics, a registered nurse, and a stroke fellow, with a neurologist at the hospital on call to evaluate the CT scans remotely as they are transmitted from the stroke ambulance.
To ensure quality of the results conducted in the stroke ambulance, sample comparisons and proficiency testing is done on the testing equipment in the ambulance, Füzéry noted. The team has the strictest requirements for the Sysmex pocH-100i hematology analyzer because the analyzer was not previously used in Alberta, and because the province's first use of the analyzer is in a mobile setting, which is atypical. Alberta's point of care office also conducts quality assurance work related to validating new devices and validating new reagent lots through split patient comparisons and linearity studies, she said.
The stroke ambulance's two-year pilot program, which began in January 2017, is scheduled to complete in May of 2019. In the current pilot, the stroke ambulance operates Monday through Friday from 8 a.m. to 6 p.m.
While stroke ambulances are still rare, they are not a novel concept. The first one was introduced in Germany more than 10 years ago, and there are a handful of stroke mobile units in operations in the US, according to a March 2017 editorial on the topic by Andrew Southerland and Ethan Brandler in the journal Neurology.
What is unique about Alberta's pilot is that it is the only such program specifically targeting rural populations, Füzéry noted.
A key factor that may be limiting the expansion of stroke ambulance programs is cost efficiency, Southerland and Brandler noted, but they acknowledged that there have not been effectiveness studies among rural populations.
"[Mobile stroke unit] deployment to date has centered mostly on health systems serving densely populated urban and suburban networks," Southerland and Brandler wrote.
A cost analysis from the first stroke ambulance in Saarland, Germany estimated that the cost ratio is favorable at distances of greater than 10 miles, and estimated that mobile stroke services could be efficient with population densities as low as 200 per square mile, they noted. As populations get more spread out, broader dispatch and delivery expenses could cut into cost-effectiveness, they suggested.
Alberta's model attempts to mitigate this issue of covering a wide area by meeting a regular ambulance halfway. The midpoint ambulance transfer is also unique to Alberta's stroke ambulance, Füzéry said.
Because the pilot is not yet completed, final results are not yet available about the effectiveness of the program, but preliminary data is promising, Füzéry noted. The stroke ambulance has had 85 deployments to date, 27 of which have been treated with intravenous tPA.
In addition, approximately 30 of the patients were diverted from the University of Alberta hospital, she said.
"These were patients who, without the stroke ambulance, would have been brought by a regular ambulance to University of Alberta Hospital," Füzéry said. "Because of the workup in the stroke ambulance, it was determined that either there might be other stroke centers that could potentially treat their disease, or the decision was made that they actually had something else other than a stroke."
Alberta Health Services will make a decision on the future of stroke ambulances in the province following the completion of the pilot, she said.
Because it is based in Edmonton, the stroke ambulance also has one final feature that the team considers to be unique to its location, Füzéry said. The ambulance has been autographed by Wayne Gretzky.