Cardiovascular diseases cost $444 billion in the U.S. each year, according to the Centers for Disease Control and Prevention. Taking low-cost aspirin to prevent heart disease and strokes seems like a no-brainer. In some cases, it is. But even aspirin, as harmless as it seems, illustrates an important maxim of health care: Every drug or procedure carries potential risk. Aspirin helps prevent dangerous clotting of the blood but increases the risk of bleeding, especially in the intestines. Too few Wisconsin residents who could benefit from preventive aspirin therapy are taking it, but so are too many people who could be harmed, a UW-Madison study found.