Diagnosis and management of peripheral arterial disease

Who is at risk? The development of atherosclerotic PAD is a multifactorial process involving both modifiable and non-modifiable risk factors. About 65% of patients also have clinically relevant cerebral or coronary artery disease, and a large prospective cohort study showed that patients with PAD have a sixfold higher risk of death from cardiovascular disease than those without PAD.1 It is therefore extremely important to identify and treat risk factors for cardiovascular disease in these patients. Age, sex, and ethnicity The incidence and prevalence of PAD increase with age. Although some studies have found prevalence to be similar in both sexes, the male:female ratio is commonly reported as 2:1 for PAD and as high as 3:1 for critical limb ischaemia. Black ethnicity is also an independent risk factor for developing PAD, with an odds ratio of 2.83.7 Smoking Smoking is the most important modifiable risk factor for developing PAD, and the causal link between the two may be even stronger than that between smoking and coronary artery disease.5 The Edinburgh Artery Study (1592 participants) found that smokers have a four times greater risk of developing intermittent claudication than non-smokers, and that patients with PAD who continue to smoke are more likely to need intervention or amputation than their non-smoking counterparts.8 9 Furthermore, a recent meta-analysis of 29 studies found that the failure rate of surgical bypass grafts is three times higher in those who continue to smoke, although this effect may be reversed by smoking cessation.10 Diabetes Diabetes is a major risk factor for PAD and more generalised cardiovascular disease, and patients with diabetes are twice as likely as those without diabetes to develop the condition.5 PAD mainly affects the infrapopliteal arteries in these patients, and glycaemic control is of paramount importance: a meta-analysis of 13 studies found that a 1% increase in glycated haemoglobin (HbA1c) is associated with a 26% increase in the risk of developing PAD.11 PAD also progresses more rapidly in those with diabetes, and these patients are five to 10 times more likely to need major amputation (above ankle level) than patients without diabetes.12 13 People with both diabetes and end stage renal disease are at particularly high risk of limb loss.14 Ulceration in patients with diabetes usually has multiple causes, and although 50% of patients with diabetes and foot ulcers have PAD, neuropathy and infection often play a major role. Patients with diabetes and foot ulceration should therefore be seen by a multidisciplinary diabetic foot team at the earliest opportunity (ideally within 24 hours).15 Hypertension and hyperlipidaemia Data from the Framingham Heart Study have shown that hypertension and hyperlipidaemia are independent risk factors for developing PAD.16 A blood pressure of greater than 160/95 mmHg increased the risk of developing intermittent claudication 2.5-fold in men and fourfold in women, and a fasting cholesterol concentration of greater than 7 mmol/L was associated with a twofold increase in the risk of claudication.16 Other factors Chronic renal insufficiency, raised haematocrit, and high concentrations of homocysteine or plasma fibrinogen also seem to be linked to an increased risk of PAD, although it is unclear whether these links are causal. bmj.com/archive Previous articles in this series Management of osteoarthritis of the knee (2012;345:e4934) Management of difficult and severe eczema in childhood (2012;345:e4770) Management of chronic epilepsy (2012;345:e4576) The diagnosis and management of tinea (2012;345:e4380) Perioperative management of patients taking treatment for chronic pain (2012;345:e4148)