Insulin Resistance Intervention After Stroke (IRIS) Trial

Among patients throughout the world who experience a transient ischemic attack (TIA)or ischemic stroke, subsequent stroke and heart attack are major causes of death and disability. Within 4 years of the initial TIA or ischemic stroke, 16 percent of patients will have a recurrent stroke and 9 percent will have a heart attack. Prevention of further vascular events, therefore, is critically important to the health of patients with stroke.

The IRIS trial will test a new treatment strategy based on evidence linking insulin resistance to increased risk for stroke and other vascular diseases. Insulin resistance is a condition in which insulin, a normal human hormone, does not work effectively because the body is resistant to its effects. This condition can lead to diabetes and is thought to cause blood vessel disease, including stroke and heart attack, in patients with and without diabetes.

Insulin resistance affects up to 50% of stroke patients and is effectively modified with thiazolidinedione (TZD) drugs used to treat type 2 diabetes. In addition to reducing insulin resistance, these drugs have other favorable effects on blood vessels, reduce blood vessel inflammation, and potentially prevent atherosclerosis. Currently marketed TZDs include rosiglitazone and pioglitazone.

The IRIS is a clinical trial that will enroll 3936 subjects at approximately 170 hospitals in Australia, Canada, Germany, Israel, Italy, the United Kingdom (UK) and the US. After an initial screening blood test, each participant will be randomly assigned to take either pioglitazone or placebo tablets. Recruitment will be completed during 2005-2012, and all participants will be followed for a minimum of 3 years.