In 2-6% of European men aged 60 plus, the major arteries supplying the brain (carotid arteries) are narrowed by 50-99%. This condition, termed carotid stenosis or atherosclerosis, accounts for 10-15% of strokes (data not in paper).

Carotid atherosclerosis is commonest in those with mild peripheral arterial disease in their legs, a condition known as claudication.

In this group the prevalence of silent carotid atherosclerosis is 15%. As they are already under the care of a vascular specialist, they are considered ideal candidates to test for silent carotid atherosclerosis.

But debate rages as to whether to screen for carotid atherosclerosis to stave off a stroke: the Royal College of Physicians does not currently recommend it, but the US Society for Vascular Surgery strongly backs testing in selected groups.

Those found to have severe (70-99%) carotid narrowing on screening are offered surgical treatment (endarterectomy).

But 133 people with claudication would need to be tested to pick up 20 patients eligible for surgery, and this would only prevent a single stroke, at a cost of around £76, 000, say the authors.

If this policy were to be introduced into England and Wales at age 60 for those with mild peripheral arterial disease, it would cost £17.5 million a year, on the basis that around 669 000 would be eligible for an ultrasound scan, 4600 of whom would then require surgery.

But all this effort would still only prevent 231 strokes, even in this high risk group, equivalent to around 0.2% of all 110,000 strokes sustained in 2010, say the authors.

"The hazards of overdiagnosis have recently been highlighted, and perhaps it is time to realise why it has been recommended that we stop testing for asymptomatic carotid atherosclerosis in the UK," they conclude.

Note: If no author is given, the source is cited instead.

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