Peripheral artery disease (PAD) is atherosclerosis of blood vessels in the legs. Atherosclerosis causes narrowing or blockage of the vessels, resulting in low blood flow to the legs. Peripheral artery disease is diagnosed by using a test called the ankle–brachial index (ABI) to show that blood pressure in the lower leg is lower than blood pressure in the arm. Risk factors for PAD include smoking, high blood pressure, high cholesterol levels, and diabetes. Peripheral artery disease may cause leg pain or heaviness that develops with walking and goes away with rest. The pain often limits the distance that people can walk. However, some people with PAD have no symptoms. For this reason, some medical experts believe that older adults should routinely have their ABI measured to screen for PAD. Screening is looking for a condition in people who have no symptoms. In addition, because people with PAD are at high risk for other conditions related to atherosclerosis, such as heart attack and stroke, some experts believe that measuring the ABI will help to determine whether people are at risk for these other conditions. The USPSTF recommended against screening for PAD in 2005 and is now updating those recommendations on the basis of new information published since then.