• Estimated 8 to 12 million Americans are affected by PAD.
• A clear association between the prevalence of PAD and increased age has been established.
• In an analysis of 2381 patients participating in the U.S. National Health and Nutrition Examination Survey, the prevalence of PAD was 4.3% overall, with a prevalence of 0.9% in patients aged between 40 and 49 years, 2.5% in patients aged between 50 and 59 years, 4.7% in patients aged between 60 and 69 years, and 14.5% in patients aged >69 years.
• A recent meta-analysis of 34 studies that examined the prevalence and risk factors of PAD worldwide shattered some preconceived notions related to this disease. With a conservative estimate of >202 million afflicted with this disease globally, this analysis showed a relative increase in PAD prevalence of 23.5% during the first decade of the new millennium. The most striking increases in prevalence were seen in low-income and middleincome countries (28.7%), although significant growth was also evident in high-income countries (13.1%)
• The economic effect of this growing burden of PAD is being experienced acutely in the United States and in many other industrialized nations. In 2001, the U.S. Medicare program spent an estimated >$4.3 billion on PAD-related treatment.
• The risk factors associated with PAD are similar to those classically identified in the context of coronary artery disease, although the relative importance of these factors appears different (Fig 1).
• Evidence of underlying PAD may be present in the absence of symptoms. For the purpose of this document, this is referred to as asymptomatic disease. Symptomatic PAD may present as intermittent claudication (IC), or with signs or symptoms consistent with limb-threatening ischemia, often referred to as critical limb ischemia (CLI). In this guidelines document, we will only consider IC within the spectrum of symptomatic PAD.
• Intermittent claudication (IC) is defined as a reproducible discomfort in a specific muscle group that is induced by exercise and then relieved with rest. Although the calf muscles are most often affected, any leg muscle group, such as those in the thigh or buttock, may be affected. This condition is caused by arterial obstruction proximal to the affected muscle bed, thereby attenuating exercise-induced augmentation of blood flow leading to transient muscle ischemia.
• Numerous population-based studies have attempted to ascertain the relative proportion of symptomatic patients amongst all those with PAD; taken in aggregate, these studies indicate that the ratio of symptomatic to asymptomatic PAD is on the order of 1:3.