Growth rates of subclinical abdominal aortic aneurysms--implications for review and rescreening programmes.

One hundred and six patients with abdominal aortic aneurysms (AAAs) of 2.5 to 3.9 cm in anteroposterior diameter were reexamined by ultrasound every 6 months for up to 3 years after diagnosis. Annual growth rates were 0.11 cm +/- 0.03 (mean +/- SE) for AAAs 2.5 to 2.9 cm and 0.29 cm +/- 0.08 for AAAs 3.5 to 3.9 cm (P = 0.002). In 73 patients (69%) the annual rate of increase in diameter was 0.2 cm or less and only 12 aneurysms (11%) grew at more than 0.5 cm per annum. We conclude that: (1) for AAAs less than 4.0 cm diameter remeasurement more often than every 6 months is unnecessary; (2) interval screening (rescreening) for AAAs more frequently than 5 yearly is unlikely to detect sufficient clinically significant aneurysms to be worthwhile.