A STATISTICAL-ANALYSIS OF THE GROWTH OF SMALL ABDOMINAL AORTIC-ANEURYSMS

Screening for abdominal aortic aneurysm has been offered to 13 000 pat ients. An overall compliance of 76% (range 51-99%) has been achieved. For those with an initial aortic diameter between 29 mm and 45 mm seri al ultrasound scans are offered to monitor aortic change. Of the 302 c ases followed up by repeated scans, 93 have had more than 5 scans (mea n of 7 scans) over a mean time period of 32.1 months (range 15-63 mont hs). The rate of change of all these aneurysms has been calculated usi ng all data points and robust linear regression. It has been possible to postulate an algorithm for aortic growth. The influence of measurem ent precision and ultrasound quality assurance on the rescan interval is demonstrated and it is suggested that 2 years is a suitable rescan interval for aortas with diameter less than 40 mm.