Which factor is non-modifiable and listed as a risk factor for peripheral arterial occlusive disease?

• A. Smoking
• B. Sedentary lifestyle
• C. Age over 55
• D. History of ischemic heart disease

Answer: (C)

Age beyond midlife is a non-modifiable risk factor for peripheral arterial occlusive disease. As people get older, the arteries naturally undergo changes such as increased stiffness, endothelial dysfunction, and a greater likelihood of atherosclerotic plaque formation. These age-related vascular changes raise the baseline risk of PAD, and this risk cannot be altered by lifestyle or medical therapy in the sense of reversing age itself.

In contrast, the other options are modifiable factors. Smoking directly accelerates atherosclerosis and damaging the endothelium, so quitting can meaningfully reduce risk. A sedentary lifestyle contributes to overall cardiovascular risk through weight gain, poorer lipid and glucose control, and reduced physical conditioning, all of which can be improved with activity. A history of ischemic heart disease reflects existing cardiovascular damage and systemic atherosclerosis, but it is not something you can change to remove the risk; rather, it signals that the person already has arterial disease.