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, there is still low levels of awareness of risk factors and symptoms, with 26% of the population the us reporting to have knowledge of pad. 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. the prevalence of pad varies considerably depending on how pad is defined, and the age of the population being studied. people diagnosed with pad have a greater risk of a mace (major adverse cardiac event) and stroke. their risk of developing a reinfarction/ stroke/ transient ischemic attack within one year following a heart attack increases to 22.9% compared to 11.4% for those without pad. the diabetes control and complications trial, and the u.k. prospective diabetes study trials, in people with type 1 and type 2 diabetes, respectively, demonstrated that glycemic control is more strongly associated with microvascular disease than macrovascular disease. pathologic changes occurring in small vessels may be more sensitive to chronically elevated glucose levels than is atherosclerosis occurring in larger arteries. research research is being done on therapies to prevent progression of pad. in those who have developed critically poor blood flow to the legs, the benefit of autotransplantation of autologous mononuclear cells is unclear. only one randomized controlled trial has been conducted comparing vascular bypass to angioplasty for the treatment of severe pad. the trial found no difference in amputation-free survival between vascular bypass and angioplasty at the planned clinical endpoint, but the trial has been criticized as being underpowered, limiting endovascular options, and comparing inappropriate endpoints. as of 2017, two randomized clinical trials are being conducted to better understand the optimal revascularization technique for severe pad and critical limb ischemia (cli), the best-cli (best endovascular versus best surgical therapy for patients with critical limb ischemia) trial, and the basil-2 (bypass versus angioplasty in severe ischaemia of the leg – 2 )trial. in 2011, pcmv-vegf165 was registered in russia as the first-in-class gene therapy drug for treatment of pad, including the advanced stage of critical limb ischemia.