The Insulin Resistance Intervention after Stroke (IRIS) trial will study the effectiveness of a commonly-prescribed medication, pioglitazone, for preventing recurrent stroke and myocardial infarction among non-diabetic patients with a recent ischemic stroke and insulin resistance. The IRIS trial represents a novel approach to stroke prevention, addressing insulin resistance, a common, but often unrecognized risk factor.
Insulin resistance may lead to diabetes, stroke and myocardial infarction. By some estimates, insulin resistance affects up to 50 percent of stroke patients. The drug being tested, pioglitazone, reduces insulin resistance and is currently approved for use in diabetes treatment, but it has not been tested for prevention of vascular disease in non-diabetic patients.
Over 400,000 Americans survive an ischemic stroke each year. Stroke is the third leading cause of death in the United States. Despite current treatment, within four years of the initial event, 16 percent of stroke patients will have a recurrent stroke and 9 percent will have a myocardial infarction. "Prevention of further vascular events, therefore, is of major importance," said principal investigator Walter N. Kernan, M.D., associate professor of medicine at Yale School of Medicine.
The IRIS trial includes over 60 research centers in the United States and Canada that will recruit 3,136 participants in the next three years. Eligible participants are men and women age 45 or over without diabetes who have insulin resistance and a recent ischemic stroke. The participants will be randomly assigned to pioglitazone or placebo in addition to their usual therapy. "We have designed the trial to test the hypothesis that pioglitazone will reduce the risk of recurrent stroke or heart attack by 20 percent during 4 years of therapy," said Kernan.
In addition to Kernan, Yale investigators include Sandra Alfano (pharmacy), Lawrence Brass, M.D. (neurology), Dawn Bravata, M.D. (medicine), Mark Gorman, M.D. (neurology), Peter Guarino (biostatistics), Ralph Horwitz, M.D. (clinical epidemiology, medicine), Silvio Inzucchi, M.D. (endocrinology), Peter Peduzzi (biostatistics), Catherine Viscoli (epidemiology), Lawrence Young, M.D. (cardiology), and over 60 collaborating neurologists in the U.S. and Canada; and Barbara Radziszewska of NINDS.