How is intermittent claudication diagnosed?

Diagnosing Intermittent Claudication

The most effective diagnostic tool for intermittent claudication is the ankle-brachial index (ABI), which should be measured in all patients presenting with symptoms of leg pain during exercise that is relieved with rest. 1, 2

Clinical Presentation and Initial Assessment

• Intermittent claudication presents as fatigue, discomfort, or pain in specific limb muscle groups during exercise that is relieved with rest 1, 2
• The pain is produced consistently by exercise and is traditionally referred to as "intermittent" claudication 1
• Symptoms can be classified according to either the Fontaine or Rutherford categories for severity assessment 1
• Vascular claudication must be distinguished from pseudoclaudication (non-vascular causes of exertional leg pain) 1, 2

Diagnostic Algorithm

1. Vascular physical examination with ABI measurement for all patients with symptoms of intermittent claudication 1
2. Exercise ABI testing if resting ABI is normal (0.91-1.30) 1
3. Alternative diagnostic strategies for patients with borderline, normal, or supranormal (>1.30) ABI:
   • Toe-brachial index 1, 2
   • Segmental pressure examination 1
   • Duplex ultrasound 1
4. Arterial imaging is NOT indicated for patients with a normal post-exercise ABI unless other causes are suspected (e.g., entrapment syndromes or isolated internal iliac artery occlusive disease) 1

Diagnostic Criteria

• Definitive diagnosis: ABI <0.90 confirms PAD 2, 3
• Exercise testing: In patients with normal resting ABI but symptoms of claudication, a decrease in ABI after exercise confirms the diagnosis 1
• Edinburgh Claudication Questionnaire: Has shown 91% sensitivity and 99% specificity for diagnosis of intermittent claudication when compared with clinical assessment 1

Differential Diagnosis

• Vascular claudication: Pain consistently produced by exercise, relieved with rest 1, 4
• Pseudoclaudication: May be caused by spinal stenosis or other neurological conditions 2, 5
• Other causes: Musculoskeletal conditions, neuropathies, or venous disease 2, 3

Common Pitfalls to Avoid

• Relying solely on symptoms: The sensitivity and positive predictive value of a classic history of claudication were only 54% and 9%, respectively, when using ABI as the gold standard 1
• Neglecting exercise testing: Normal resting ABI does not exclude PAD; exercise testing can unmask PAD not evident at rest 1, 2
• Overlooking comorbid cardiovascular disease: Up to 60-80% of patients with PAD have significant coronary artery disease 1, 4
• Assuming all leg pain is vascular: Consider neurological, musculoskeletal, and metabolic causes 2, 5

Next Steps After Diagnosis

• After confirming diagnosis, assess cardiovascular risk factors as patients with PAD have a 2-4 fold excess risk of coronary artery disease 1, 4
• Consider pharmacological treatment with cilostazol, the only FDA-approved medication for symptomatic treatment of claudication 6, 3
• Implement supervised exercise therapy, which has been shown to increase walking distance by up to 240% after 6 months 7
• Provide comprehensive risk factor modification and antiplatelet therapy 1, 5

By following this diagnostic approach, clinicians can accurately diagnose intermittent claudication and initiate appropriate management to improve symptoms and reduce cardiovascular risk.