New guidelines recommend aspirin use in primary prevention for people ages 40 to 70 years old who are at higher risk of a first cardiovascular event, but not for those over 70. Yet, people over 70 are at higher risks of cardiovascular events than those under 70. As a result, health care providers are understandably confused about whether or not to prescribe aspirin for primary prevention of heart attacks or strokes, and if so, to whom.