Abdominal Aortic Aneurysm (AAA) rupture rate in the UK justifies the current surveillance programs and bring ease to some physicians that at some point have cast a shadow on their efficacy. This study also endorses reference thresholds to intervene patients.
In 2009, the UK National Health Service (NHS) implemented a AAA national surveillance scheme where men over 65 were eligible for screening. Those with ≥5.5 cm aneurysms were sent to consult with a vascular surgeon, while those with smaller aneurysms were invited to enter an ultrasound surveillance program.
AAA treatment guidelines were published in 2003, estimating a 3 to 15% rupture risk for aneurysms between 5 and 5.9 cm. More recent guidelines have estimated a 1% rupture risk a year for aneurysms under 5.5 cm.
This study looked at over 18,000 men between 2009 and 2017 that took part in the surveillance scheme and starting with AAA between 3 and 5.5 cm. The study did not include women, since AAA incidence in women is significantly lower.
During the follow up period, some 1763 patients reached 5.5 cm or higher measures and were referred to a peripheral vascular physician for definite treatment. Some 83 with smaller aneurysms were also sent to a specialist based on their symptoms, rapid growth and other alarming signs. Finally, 31 patients had aneurysm rupture, and 29 of these patients died.
These figures result in an estimated risk of 1 in 100 patients/year for all diameters bellow 5.5 cm.
Risk is in direct correlation with diameter: it goes from 0.03% for smaller aneurysms (between 3 and 4.4 cm) to 0.4% for AAA right below the reference threshold (5.0 to 5.4 cm).
Since rupture risk in this cohort is so low, we can conclude that the surveillance program is safe.
Original title: Safety of men with small and medium abdominal aortic aneurysms under surveillance in the national health service screening program.
Reference: Oliver-Williams C et al. Circulation. 2019; Epub ahead of print.
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