Recommendations for screening intervals for small aortic aneurysms

Background: The aim was to determine the optimum rescreening interval for small abdominal aortic aneurysms (AAAs). Methods: Data from 12 years of population screening of 65-year-old men were analysed and 1121 small AAAs (less than 4·0 cm in initial diameter) were divided into groups: group 1 (2·6–2·9 cm; n = 625), group 2 (3·0–3·4 cm; n = 330) and group 3 (3·5–3·9 cm; n = 166). Expansion rate and the cumulative proportions to expand to over 5·5 cm, or require surgery, or rupture were calculated. Results: Expansion rate was related to initial aortic diameter: 0·09 cm per year in group 1, 0·16 cm per year in group 2 and 0·32 cm per year in group 3 (P < 0·001). Aneurysms in 2·4 per cent of patients in group 1 exceeded a diameter of 5·5 cm or required surgery within 5 years; there were no ruptures. In group 2, no aorta exceeded 5·5 cm but at 3 years 2·1 per cent had reached 5·5 cm and 2·9 per cent had required surgery. The rupture rate at 3 years was zero. In group 3, the aneurysm diameter exceeded 5·5 cm in 1·2 per cent of patients, but no patient required surgery or experienced rupture within 1 year; at 2 years 10·5 per cent of aneurysms had exceeded 5·5 cm in diameter or required surgery and 1·4 per cent had ruptured. Conclusion: The appropriate rescreening interval can be determined by initial aortic diameter in screened 65-year-old men. AAAs of initial diameter 2·6–2·9 cm should be rescanned at 5 years, those of 3·0–3·4 cm at 3 years and those of 3·5–3·9 cm at 1 year. Copyright © 2003 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.