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Welcome to IRIS, the Insulin Resistance Intervention after Stroke Trial

Stroke affects millions of people throughout the world every year. About one in ten patients die of their stroke, making it the third leading cause of death. Among the many people who survive, about half are left with significant disability and recurrence is common. A major goal for public health is to prevent recurrence and keep people healthy after stroke.

Stroke is a disease involving the blood vessels leading to or within the brain. The most common type of stroke, ischemic stroke, occurs when one of these blood vessels is blocked, depriving a part of the brain of oxygen and nutrients. Depending on what part of the brain is affected, a stroke can cause sudden weakness in an arm or leg, difficulty speaking, or other symptoms. Transient ischemic attacks are stroke-like events that last less than 24 hours and do not produce permanent brain damage.

Despite current treatment, one in four patients with stroke or TIA will have a stroke or heart attack within five years of their initial event. Prevention of further vascular disease complications, therefore, is a major goal in the care of patients with stroke and TIA.

The Insulin Resistance Intervention after Stroke (IRIS) trial is a randomized clinical trial that will test the effectiveness of a new approach to preventing stroke and heart attack among patients with a recent stroke or TIA. The new approach targets insulin resistance, a newly-recognized cause of atherosclerosis. Atherosclerosis is the underlying disease that clogs vessels in strokes and heart attacks. Insulin resistance affects nearly half of all patients with stroke and ischemic TIA.

Participating stroke patients will be assigned to receive pioglitazone, a medication which reduces insulin resistance, or placebo (an inactive look-alike pill). Patients will stay on their assigned treatment for about four years. At the end of the study, investigators will compare the experience of patients on pioglitazone and placebo to see which group had fewer recurrent strokes and heart attacks.