most common cause of PAD is a buildup of plaque inside the arteries, called atherosclerosis, which reduces the flow of blood to the extremities. Most people with early PAD do not experience symptoms. However, if left untreated, PAD may progress to the point that the muscles are starved for oxygen when a person uses them to walk or climb stairs. The resulting pain, called claudication, is usually intermittent, that is, it goes away when the person stops exercising. In more severe cases of PAD, the person may experience pain even when resting, and leg or foot wounds may not heal normally. In a small percentage of cases, the circulation of blood may become so reduced that severe ischemic muscle damage results, and amputation may be required.

Medically, PAD is of grave concern because it is a strong sign of systemic atherosclerosis and thus a high risk of a heart attack, ischemic stroke, and vascular death. The risk of heart attack is 20 to 60 percent higher, the risk of stroke is 40 percent higher, and the risk of death from coronary heart disease is two to six times higher than in people without PAD (Hirsch et al., 2006). Several studies have shown that the more severe the symptoms of PAD, the higher the mortality rate due to heart attack or stroke (Belch et al., 2003).

PAD itself rarely causes death (unless an ischemic limb is untreated for too long), but it can cause substantial morbidity and disability. Individuals with PAD have a reduced peak exercise capacity that limits their range of physical functioning. For example, they have less capacity to walk than otherwise similar individuals without PAD. If they have progressed to intermittent claudication, they have substantial limitations on their capacity to walk. In severe cases, claudication, muscle weakness or numbness, ischemic leg pain at rest, or ulceration will interfere with a person’s ability to work.

EPIDEMIOLOGY

According to the National Health and Nutrition Examination Survey (NHANES), approximately 5 percent of U.S. adults ages 40 or older (more than 5 million individuals) had PAD (defined as an ankle-brachial index [ABI] of less than 0.90 in either leg) for the period 1999 to 2002 (PauloseRam et al., 2005). Of these, approximately one-fourth had moderate to severe PAD, defined as an ABI less than 0.70 in either leg. These rates went up sharply with age and were higher among men than women, among non-Hispanic blacks than among non-Hispanic whites or Mexican Americans, and in individuals with diabetes than nondiabetic individuals. A more recent systematic review of U.S. prevalence, that included NHANES findings

diseases in 2008, including the use of the term peripheral artery disease in place of peripheral arterial disease or peripheral vascular disease (Hiatt et al., 2008a).



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