Clot-busting drugs are known as thrombolytics, and tissue plasminogen activator (tPA) is the only FDA-approved thrombolytic for treating acute ischemic stroke, which is caused by a blood clot in the brain.

Although the study didn't follow patients after hospital discharge, "we believe that the increased treatment rate has the potential to reduce the overall burden of stroke disability and morbidity," said Opeolu Adeoye, M.D., lead author of the study and assistant professor of emergency medicine and neurosurgery at the University of Cincinnati in Ohio.

Using Medicare records and pharmacy billing codes, researchers found 1.1 percent to 1.4 percent of acute ischemic stroke patients received a thrombolytic drug in 2005, and 3.4 percent to 3.7 percent did in 2009.

In a further calculation, the researchers assumed that some or all of the billings for unapproved thrombolytics and/or treating hemorrhagic stroke were billing errors, or represented an ischemic stroke that subsequently developed some bleeding, which occasionally occurs. This upped the use of tPA, Adeoye said, which led to a conservative estimate that 3.4 percent to 5.2 percent -- or 23,800 to 36,000 of the 700,000 Americans who had an ischemic stroke in 2009 -- received tPA.

Treatment with a clot-busting drug is most effective as soon as possible after stroke symptoms begin -- ideally within the first hour, according to American Heart Association/American Stroke Association guidelines. But, doctors can give tPA to some patients up to 4.5 hours after symptoms begin.

Co-authors are Richard Hornung, Ph.D.; Pooja Khatri, M.D.; and Dawn Kleindorfer, M.D.

Note: If no author is given, the source is cited instead.

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