PAD carries a greater than "20% risk of a coronary event in 10 years".The risk is low that an individual with claudication will develop severe ischemia and require amputation, but the risk of death from coronary events is three to four times higher than matched controls without claudication. Of patients with intermittent claudication, only "7% will undergo lower-extremity bypass surgery, 4% major amputations, and 16% worsening claudication", but stroke and heart attack events are elevated, and the "5-year mortality rate is estimated to be 30% (versus 10% in controls)". Epidemiology
The prevalence of PAD in the general population is 3–7%, affecting up to 20% of those over 70; 70%–80% of affected individuals are asymptomatic; only a minority ever require revascularisation or amputation. Peripheral artery disease affects one in three diabetics over the age of 50. In the US, it affects 12–20 percent of Americans age 65 and older. Around 10 million Americans have PAD. Despite its prevalence and cardiovascular risk implications, only 25% of PAD patients are undergoing treatment.In people aged 40 years and older in the United States in 2000, rates of PAD was 4.3%. Rates were 14.5% people aged 70 years or over. Within age groups, rates were generally higher in women than men. Non-Hispanic blacks had a rates of 7.9% compared to 4.4% in Non-Hispanic whites and 3.0% (1.4%–4.6%) in Mexican Americans.The incidence of symptomatic PAD increases with age, from about 0.3% per year for men aged 40–55 years to about 1% per year for men aged over 75 years.
This system was created on the basis of ischemia and angiographic disease patterns not being the sole determinants of amputation risk. The WIfI classification system is broken up into two parts: wounds and ischemia. Wounds are graded 0 through 3 on the presence of ulceration and/or gangrene and ischemia. Grade 0: no ulcer, no gangrene
Grade 1: small, shallow ulcer; no gangrene
Grade 2: deep ulcer with exposed tendon or bone, gangrene limited to toes
Grade 3: extensive, full-thickness ulcer; gangrene extending to forefoot or midfootIschemia is graded 0 through 3 based on ABI, ankle systolic pressure, and toe pressure. Grade 0: ABI 0.8 or higher, ankle
Grade 1: arterial brachial index 0.6 to 0.79, ankle pressure 70 to 100 mm Hg, toe pressure 40 to 59 mm Hg
Grade 2: ABI 0.4–0.59, ankle pressure 50 to 70 mm Hg, toe pressure 30 to 39 mm HgThe TASC (and TASC II) classification suggested PAD treatment is based on the severity of disease seen on angiogram. Screening
It is not clear if screening for disease in the general population is useful as it has not been properly studied. This includes screening with the ankle-brachial index.Testing for coronary artery disease or carotid artery disease is of unclear benefit. While PAD is a risk factor for abdominal aortic aneurysms (AAA), there is no data on screening individuals with asymptomatic PAD for abdominal aortic aneurysms. In people with symptomatic PAD screening by ultrasound for AAA is not unreasonable.