Risk Factors for Stroke

Stroke risk is increased by conditions that promote thrombosis, embolism, or vascular injury. Each statement is analysed below.

• 1. Sickle cell disease — Sickling of red blood cells causes vaso-occlusion, chronic haemolysis, and endothelial injury, leading to both large-vessel (moyamoya-like) and small-vessel cerebrovascular disease. Sickle cell disease is a well-recognised, important cause of stroke, especially in children. Correct.
• 2. Cigarette smoking — Smoking accelerates atherosclerosis, increases blood viscosity and fibrinogen levels, promotes platelet aggregation, and causes endothelial dysfunction — all of which raise the risk of both ischaemic and haemorrhagic stroke. It is one of the most important modifiable risk factors for stroke. Correct.
• 3. Hypofibrinogenaemia — This statement is incorrect as written. It is elevated (not low) fibrinogen — hyperfibrinogenaemia — that is an established risk factor for stroke, since high fibrinogen promotes hypercoagulability and atherogenesis. Hypofibrinogenaemia, in fact, impairs clot formation and is associated with a bleeding tendency rather than thrombosis. Incorrect.
• 4. Atrial fibrillation — AF causes stasis of blood in the left atrium/atrial appendage, predisposing to thrombus formation and subsequent cardioembolic stroke. It is one of the leading identifiable causes of ischaemic stroke, particularly in the elderly. Correct.

Conclusion

Sickle cell disease, cigarette smoking, and atrial fibrillation (statements 1, 2 and 4) are all established risk factors for stroke, whereas hypofibrinogenaemia (statement 3) is not — it is hyperfibrinogenaemia that carries increased risk. Hence, the correct combination is 1, 2 and 4.