BOSTON—The number of patients with ischemic stroke who receive t-PA has increased during the past several years, but is still low, according to data presented at the 2012 Annual Meeting of the American Neurological Association. The main reason for the low treatment rate is that few patients are eligible to receive t-PA, and some neurologists believe that the exclusion criteria for t-PA may need to be revisited, said Dawn Kleindorfer, MD.
The certification of hospitals as primary stroke centers is associated with increased rates of t-PA treatment, said Dr. Kleindorfer, Professor of Neurology at the University of Cincinnati, who conducted several epidemiologic studies to identify trends in the management of acute stroke. Intra-arterial therapy is increasing at a faster rate than IV therapy, she added, but the former treatment has not been shown to be superior to the latter.
Primary Stroke Center Certification May Increase the Rate of t-PA Treatment
Less than 1% of American patients with ischemic stroke received t-PA in 2001. In 2004, after initiation of the Joint Commission’s Primary Stroke Center Certification Program, the rate of t-PA treatment began to increase. The Centers for Medicare and Medicaid Services increased reimbursement for t-PA treatment in 2006, and by 2009, 4.5% of ischemic stroke patients were receiving t-PA, noted Dr. Kleindorfer.
At hospitals that later were certified as primary stroke centers, the rate at which patients with ischemic stroke received t-PA began increasing three years before certification. The rate of t-PA treatment continued to increase for three years after certification, added Dr. Kleindorfer. Rates of providing t-PA also increased slightly at hospitals that were not certified as primary stroke centers. “What would be really interesting is to see how the comprehensive stroke center certification, which is just starting this year, will further impact treatment rates,” said Dr. Kleindorfer.
Arrival Time Is the Biggest Exclusion Factor for t-PA
Between 6% and 8% of all patients with ischemic stroke are eligible to receive t-PA. The biggest reason for ineligibility by far is that patients do not arrive at the hospital on time (ie, within three hours of symptom onset) to receive t-PA. Approximately 77% of patients present at a hospital with stroke at greater than three hours from symptom onset, noted Dr. Kleindorfer.
Patients with stroke tend to arrive at the hospital “very early or very late,” she continued. Early patients usually arrive within two hours of stroke onset, and late patients often arrive days after stroke onset. Arrival times have not improved, despite national media campaigns to increase awareness, said Dr. Kleindorfer.
European studies have suggested expanding the time window during which a patient may receive t-PA from three hours to 4.5 hours, but the idea is controversial, and the FDA has not approved this expansion. Because many patients with stroke do not arrive at the hospital within 4.5 hours, expanding the time window might not increase the rate of t-PA treatment, said Dr. Kleindorfer.
The European Cooperative Acute Stroke Study III suggested that expanding the time window to 4.5 hours would increase the amount of patients eligible for t-PA by 0.5%, which may have little effect on public health, said Dr. Kleindorfer. The study’s exclusion criteria may have influenced its results, she added. Investigators excluded patients with stroke who were older than 80, which reduced the trial’s potential population by 30%, said Dr. Kleindorfer. Excluding patients with a history of prior stroke and diabetes also reduced the size of the cohort.
Medical Factors Prevent Some Patients With Stroke From Receiving t-PA
Medical exclusions such as mild stroke severity and high blood pressure also make some patients with stroke ineligible to receive t-PA, although they are less common exclusion criteria than late arrival time. If every patient with ischemic stroke arrived at the hospital on time, 30% would be eligible to receive t-PA, said Dr. Kleindorfer.
In contrast to what might be expected, increased age was associated with greater eligibility for t-PA, according to Dr. Kleindorfer. The greater eligibility mostly resulted from the increased severity of infarcts among older patients. Nearly 10% of patients older than 85 were eligible for t-PA, compared with 3% of patients between ages 18 and 44. Despite their eligibility, however, older patients may be less likely to be treated with t-PA in the US, Dr. Kleindorfer said.
Intra-Arterial Stroke Treatment Is Increasing
Intra-arterial treatment of acute ischemic stroke is becoming much more common. In the last two years, the rate of embolectomy has increased. Neurologists performed about 10% of intra-arterial embolectomies in the United States between 2008 and 2010, said Dr. Kleindorfer. Radiologists and neurosurgeons performed the vast majority of these procedures. IV delivery of t-PA also has been increasing, but at a lower rate than intra-arterial delivery.