tPA drug may improve outcomes in mild stroke patients


Treating mild strokes with the clot-busting drug approved for severe stroke could reduce the number of patients left disabled and save US$200 million a year in disability costs, according to a study presented at the American Stroke Association’s International Stroke Conference 2011.


In the study funded by the National Institutes of Health, researchers analysed hospital records from 437 patients diagnosed with mild ischaemic stroke at 16 sites in the Greater Cincinnati/Northern Kentucky region in 2005. The patients arrived at the hospital within the 3.5 hours, well within the 4.5 hour window for treatment with intravenous tissue plasminogen activator (tPA).


The federal government has approved the clot-busting drug for ischaemic strokes, which accounts for 87% of all strokes. It is the only acute stroke drug that can reduce disability but remains unproven for treating mild stroke.


“Currently, there is no standard of treatment for patients with the mildest strokes, even if they come into the emergency department quickly enough for intravenous tPA, the only proven treatment for a more serious stroke,” said Pooja Khatri, lead researcher of the study and associate professor in the department of Neurology and director of Acute Stroke at the University of Cincinnati Academic Health Center in Ohio.


“The pivotal randomised trials that proved tPA’s usefulness excluded mild stroke patients because it was thought that they generally did well and the risk of tPA treatment, which includes a slight but significant risk of life-threatening bleeding in the brain, would not be worth the benefit,” she said.


Only four of the mild stroke patients (less than 1%) received tPA. The researchers identified 150 of the remaining patients as likely candidates for the drug if the mildness of their stroke was disregarded as a reason to deny them tPA treatment.


Based on the findings, the researchers then excluded those with baseline disability (estimated at 37%) and assumed that 8% to 13% of the remaining mild stroke patients would regain independence after their stroke if tPA was as effective as it was in more serious cases.


Extrapolating to the US population, the researchers said that if tPA proves effective, 2,176 to 5,613 fewer patients would be disabled from mild stroke each year — saving an estimated US$200 million in disability expenditures.


In the last five years, researchers conducting several studies have found that about a third of patients who experienced mild strokes remained disabled three months after initial hospitalisation.


“It was believed that patients with milder strokes would recover from these events,” Khatri said. “These findings raise the question of whether the mildest strokes should be treated with intravenous tPA.”