[Optimal interval screening and observation of abdominal aortic aneurysms].

Introduction: Screening and observation of abdominal aortic aneurysms (AAA) produce psychological stress. Consequently, safe and optimal intervals of rescreening and observation must be developed.

Method: In a randomised, mass screening trial of 6,339 men aged, 65-73 years from 1994 to 1998, 76% attended, and 191 (4%) had AAA > or = 3 cm. Twenty-four (0.5%) had AAA above 5 cm in diameter and were referred for surgery, while the rest were offered annual control. Later, all 348 (7.5%) men who, 3 to 5 years before, had had an ectatic aorta (an infrarenal aortic diameter of 25-29 mm or a distal/renal aortic diameter ratio of > 1.2) were offered rescreening, together with a control group of 380 men.

Results: None of the controls had developed AAA. Of those who initially had an aortic diameter of 25-29 mm aorta, 28.5% had developed AAA (size range 30-48 mm), whereas only 3.5% with a ratio > 1.2 developed AAA (size range 30-34 mm). During the fourth year of surveillance some AAA initially sized below 3.5 cm expanded to above 5 cm, whereas this occurred in some sized 3.5-3.9 cm during the second year and in most above 4 cm did during the first year of observation.

Conclusion: Rescreening for AAA can be restricted to initially ectatic aortas sized 25-29 mm at five-year intervals. Observation of small AAA can be restricted to 1-4 year intervals.