Make the Diagnosis: Peripheral Arterial Disease
Prior Probability of Peripheral Arterial Disease
Clinical examination findings for peripheral arterial disease of the legs must be interpreted in the context of the pretest probability. The prevalence varies with risk factors, but for general screening age is an important risk factor. By age 60, the prevalence of asymptomatic peripheral arterial disease is 5% and increases to 12% by age 70.1, 2 Patients 60 years and older with leg discomfort have a peripheral arterial disease prevalence of 15%.3
Population in Whom Peripheral Arterial Disease Should Be Considered
Patients at risk for peripheral arterial disease include those of older age, with a history of vascular risk factors especially smoking, or diabetes, or atherosclerotic disease (stroke or myocardial infarction), but current recommendations do not support routine screening of the general population.4 Lower extremity symptoms and signs that should prompt an evaluation include pain, ulcers, or change in skin color of legs or feet. When assessing a patient with leg discomfort, a clinician should consider peripheral arterial disease in the differential diagnosis (Box 72-1).
Box 72-1Differential Diagnoses for Leg Discomforta |Favorite Table|Download (.pdf) Box 72-1 Differential Diagnoses for Leg Discomforta
|Arthritis of knees or hips |
|Ischemic intermittent claudication |
|Mechanical muscle pain |
|Nerve root pain, sciatica, neurogenic pseudoclaudication (spinal stenosis) |
|Peripheral nerve pain (eg, diabetic neuropathy) |
|Phlebitic syndrome after deep venous thrombosis |
|Reflex sympathetic dystrophy |
|Thromboangiitis obliterans (Buerger disease) |
|Venous claudication |
Assessing the Likelihood of Peripheral Arterial Disease
The clinical examination focuses on skin changes, pulses, and bruits (see Table 72-1). At the bedside, the clinician should use a Doppler probe to listen for the number of arterial components in the posterior tibial pulse and to measure the ankle-brachial index (see Figure 72-1). Inexperienced clinicians can practice listening to the number of arterial components by listening to their own radial pulses or audio recordings. (See also video “Doppler Auscultation of the Posterior Tibial Artery” available at http://jama.ama-assn.org/cgi/content/full/295/5/536/DC1.) Individual findings are as good as combinations of findings for identifying affected patients. However, combinations of normal findings are more efficient for identifying patients without peripheral arterial disease.
Table 72-1Useful Findings for Diagnosing Peripheral Arterial Disease (PAD) |Favorite Table|Download (.pdf) Table 72-1 Useful Findings for Diagnosing Peripheral Arterial Disease (PAD)
| ||LR+ (95% CI) ||LR- (95% CI) |
| ||Screening settings |
|Claudicationa ||3.3 (2.3-4.8) ||0.89 (0.78-1.0) |
|Femoral bruit ||4.8 (2.4-9.5) ||0.83 (0.73-0.95) |
|Any pulse abnormality ||3.1 (1.4-6.6) ||0.48 (0.22-1.0) |
| ||Symptomatic patients |
|Cool skin ||5.9 (4.1-8.6) ||0.92 (0.89-0.95) |
|Presence of a iliac, femoral, or popliteal bruit...|
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