Researchers estimate that an effective treatment for mild ischemic stroke could prevent more than 2,000 disabilities each year in the United States.
LOS ANGELES—If tissue plasminogen activator (t-PA) proves to be an effective treatment for mild ischemic stroke, it could prevent disability in more than 2,000 patients in the United States each year. Those were the conclusions of Pooja Khatri, MD, Director of Acute Stroke at the University of Cincinnati Academic Health Center, and colleagues, as presented at the 2011 International Stroke Conference.
“I think we clearly show that an effective treatment would have a major public health impact,” said Dr. Khatri. “So with that in mind, clearly, a more systematic study of mild ischemic stroke is needed.” She added that a large-scale, two-part trial of t-PA in mild ischemic stroke is being developed.
Dr. Khatri and colleagues extrapolated data from the Greater Cincinnati/Northern Kentucky region to estimate the potential national impact of t-PA for mild ischemic stroke if such a treatment proves effective. The treatment is currently approved only for severe stroke, and data on its effectiveness for mild stroke are limited. Mild ischemic stroke results in substantial disability each year.
The researchers performed a retrospective chart review of 16 hospitals in the study region, which has a population of more than 1.3 million, to look for patients who presented with mild ischemic stroke within 3.5 hours from stroke onset in 2005. They defined mild ischemic stroke as having an NIH Stroke Scale score of 5 or less at presentation. Patients’ eligibility for t-PA was determined using NINDS criteria for patients presenting earlier than two hours and using European Cooperative Acute Stroke Study III criteria for patients presenting between two and 3.5 hours. The investigators excluded patients with baseline disability, defined as a pre-stroke modified Rankin Scale score of 2 to 6.
According to these criteria, 441 patients presented with ischemic stroke within 3.5 hours during the study period. Among this population, 190 (43%) did not have mild ischemic stroke, 247 (56%) had mild ischemic stroke but did not receive t-PA, and four (1%) had mild ischemic stroke and did receive t-PA. Of the patients with mild ischemic stroke who did not receive t-PA, 150 (62%) had been eligible for the treatment.
By extrapolating these data, the researchers estimated that 43,180 patients—27,203 of whom are without baseline disability—present with mild ischemic stroke and are eligible for t-PA each year in the US. Assuming that t-PA would have a treatment effect of 8% to 13% in these patients, the treatment could prevent 2,176 to 3,761 disabilities and save $200 million annually, according to the researchers.
Dr. Khatri noted that there are three types of patients who present with stroke that is considered too mild to treat but who eventually develop disabilities.
“One is the patient who presents with so-called mild symptoms, but for whom we’re not appreciating the full extent of the deficit in the emergency department,” she said. “The second is the patient with extension of stroke symptoms, which we know is very common. A significant portion of patients worsen in their stroke scores over subsequent days. And the third possibility is a relatively sick patient with vascular and other comorbidities. Certainly the third patient wouldn’t be impacted by treatment t-PA, but the first two patients would. But the literature is fairly limited in patients with mild ischemic stroke, which is why we really need some large systematic study of these patients.”
—Jack Baney