A 58-year-old Indian man with diabetes and hypertension is diagnosed with peripheral arterial disease of the lower limbs. What is the most common cause of peripheral arterial disease in this patient?

Explanation

## Most Common Cause of PAD **Key Point:** Atherosclerosis is the most common cause of peripheral arterial disease worldwide, accounting for >90% of all PAD cases in developed countries and 80–85% in developing countries like India. ### Etiology of Peripheral Arterial Disease | Cause | Frequency | Risk Factors | Geography | |-------|-----------|--------------|----------| | **Atherosclerosis** | >90% (developed); 80–85% (India) | Age, smoking, diabetes, hypertension, dyslipidemia | Global; most common | | Thromboangiitis obliterans | 5–10% (India); <1% (West) | Young males, heavy smokers | India, Middle East, East Asia | | Takayasu arteritis | 1–2% (India); <0.1% (West) | Young women, autoimmune | India, Asia | | Fibromuscular dysplasia | <1% | Young women, renal arteries | Rare; usually renal/carotid | **High-Yield:** In India, while thromboangiitis obliterans is more prevalent than in Western countries, atherosclerosis still remains the **single most common cause** of PAD. The rising prevalence of diabetes and hypertension in India has further increased atherosclerotic PAD. ### Clinical Pearl In a 58-year-old patient with **diabetes and hypertension**, atherosclerosis is virtually certain. These are classic risk factors for atherosclerotic PAD. Thromboangiitis obliterans typically affects **young men (20–40 years) with heavy smoking history** and presents with **digital ischemia and gangrene**, not typical claudication. ### Distinguishing Features ```mermaid flowchart TD A[Peripheral Arterial Disease]:::outcome --> B{Age and Risk Factors?}:::decision B -->|Age >50, DM, HTN, smoking| C[Atherosclerosis]:::action B -->|Age 20-40, heavy smoker, male| D[Thromboangiitis obliterans]:::action B -->|Young woman, constitutional symptoms| E[Takayasu arteritis]:::action C --> F[Proximal/distal involvement, claudication]:::outcome D --> G[Distal digital ischemia, gangrene]:::outcome E --> H[Upper limb + lower limb, systemic features]:::outcome ``` **Mnemonic:** **AAAA** — **A**therosclerosis is the **A**lmost **A**lways **A**nswer for PAD in older patients. ### Why Atherosclerosis in This Patient 1. **Age**: 58 years — peak incidence for atherosclerotic PAD 2. **Diabetes**: Major risk factor; accelerates atherosclerosis 3. **Hypertension**: Endothelial injury and plaque formation 4. **Typical presentation**: Claudication (not digital gangrene, which would suggest Buerger's) [cite:Robbins 10e Ch 11; Harrison 21e Ch 246]