A 58-year-old man with hypertension and dyslipidemia is found to have peripheral arterial disease on screening. Which is the most common cause of peripheral arterial disease in developed countries?

Explanation

## Most Common Cause of PAD **Key Point:** Atherosclerosis is the most common cause of peripheral arterial disease in developed countries, accounting for >90% of all PAD cases [cite:Harrison 21e Ch 297]. ### Epidemiology and Risk Factors Atherosclerotic PAD is driven by classic cardiovascular risk factors: - Smoking (strongest modifiable risk factor) - Hypertension - Dyslipidemia - Diabetes mellitus - Age >40 years - Male sex ### Comparison of Major Causes of PAD | Cause | Prevalence | Geography | Key Features | Typical Patient | |-------|-----------|-----------|--------------|----------------| | Atherosclerosis | >90% | Developed countries | Segmental, proximal > distal | Age >50, smoker, HTN, DM | | Thromboangiitis obliterans | 5–10% | Middle East, Asia, Eastern Europe | Segmental, distal > proximal, superficial thrombophlebitis | Young male smoker, <45 years | | Takayasu arteritis | <1% | Asia, Middle East, Africa | Large vessel, aorta and branches | Young female, systemic symptoms | | Fibromuscular dysplasia | <1% | Developed countries | Renal/carotid > peripheral | Young to middle-aged women | ### Clinical Pearl **High-Yield:** In India and developing countries, while atherosclerosis remains the leading cause in older patients, thromboangiitis obliterans (Buerger disease) has a higher relative prevalence than in Western countries, particularly in young male smokers. However, globally and in most developed healthcare settings, atherosclerosis dominates. ### Distinguishing Features **Atherosclerotic PAD:** - Proximal and distal vessels affected - Segmental lesions with skip areas - Associated with metabolic syndrome - Responds to statin and antiplatelet therapy **Thromboangiitis Obliterans:** - Distal vessels predominantly (tibial, peroneal, radial, ulnar) - Migratory superficial thrombophlebitis - Absence of atherosclerosis on histology - Mandatory smoking cessation for disease arrest **Tip:** When a young male smoker (<45 years) presents with distal PAD and superficial thrombophlebitis, suspect Buerger disease. When an older patient with metabolic risk factors has proximal PAD, atherosclerosis is the answer.