Between 5% and 10% of men aged 65 to 79 have abdominal aortic aneurysms, but don't know it. If their weakened arteries burst they stand a very high risk of dying. Ultrasound screening of men in this age group can significantly reduce the numbers of men who die from this condition. The overall benefits of screening are complex, however, because many men may be subjected to unnecessary anxiety and/or to the complications of surgery.
An aneurysm is a localised widening of an artery. It occurs because the artery wall is weakened and without treatment it could easily burst. If the aneurysm is in the aorta, the main artery that carries blood through the abdomen, the result often can be fatal. Doctors believe that any abdominal aortic aneurysm that is greater than 5cm is at a high risk of bursting.
To see whether a program of ultrasound screening could detect these aneurysms before they burst, and save lives as a result, Cochrane Researchers performed a systematic review of screening trials. They identified four controlled trials that were conducted in the UK, Denmark and Australia, and involved a total of 127,891 men and 9,342 women.
The results showed that men aged 65-79 could benefit from screening, but there were insufficient data on women (whose risk of death from ruptured aortic aneurysm is much lower than the risk in men) to ascertain effectiveness in women.
Understanding the nature of this benefit is complex. Screening detects aneurysms before they burst, and the opportunity to repair them early significantly reduced deaths from aortic aneurysms. However, not everyone with an aneurysm will die as a result, even if it is not repaired, and so some people whose aneurysm would not have otherwise burst are subjected to major surgery with its attendant complications or to anxiety about their unoperated aneurysm through screening. Screening had no significant effect on overall mortality, which is to be expected given that aortic aneurysm is relatively infrequent as a cause of death.
"The overall population benefit from screening appears to be established, in that fewer people died from their aortic aneurysm as a result of screening. However, there will still be some deaths and ill health resulting in a small number of people dying or suffering ill health as a result of elective aneurysm repair, who otherwise consider themselves healthy, and whose aneurysms detected by screening may not have ruptured in the future. Patients may therefore be asked to undergo risky surgery for a procedure that may not have killed them, others may discover small aneurysms and worry about them unnecessarily," says lead author Dr Paul Cosford, Director of Public Health at the East of England Strategic Health Authority.
"Resource analysis indicates that screening may be cost effective in relatively developed countries, but that this needs further expert analysis particularly given the lack of information on life expectancy, complications of surgery or quality of life," says Cosford. The researchers say there is a need to see whether surveying a larger population of women would demonstrate that they could benefit from screening as well.