The natural history of abdominal aortic aneurysms and their risk of rupture

The UK Small Aneurysm Trial has shown that ultrasound surveillance is a saf e management option for patients with small abdominal aortic aneurysms (4.0 to 5.5 cm in diameter), with an annual rupture rate of only 1%. We investi gated baseline risk factors associated with aneurysm rupture in the 1090 tr ial patients and an additional 1167 patients enrolled in the UK Small Aneur ysm Study. In this cohort of 2257 patients there were 103 cases of aneurysm rupture. After 3 years the annual rate of rupture was 2.2% (95% CI 1.7 to 2.8). The risk of rupture was independently and significantly associated wi th female sex (p < 0.001), larger initial aneurysm diameter (p < 0.001), cu rrent smoking (p = 0.01) and higher mean blood pressure (p = 0.01). Age, bo dy mass index, serum cholesterol concentration and ankle/brachial pressure index were not associated with an increased risk of aneurysm rupture. The most surprising finding was that women had a 3-fold higher risk of aneu rysm rupture than men. Effective control of blood pressure and cessation of smoking are two simple measures that are likely to diminish the risk of an eurysm rupture and improve the cardiovascular health of patients with abdom inal aortic aneurysm.