Strategies to improve the effectiveness of abdominal aortic aneurysm screening programmes

Ruptured abdominal aortic aneurysms (rAAAs) occurring in patients with screen-detected aneurysms could be regarded as a failure of screening and reduce effectiveness of screening. To understand this issue, we studied the reasons why rAAAs occur in screened patients and estimated the cost-benefit ratio if these ruptures could be prevented.

All rAAAs occurring in the Huntingdon district in the UK during the study period (1991-2000) were traced via a combination of hospital admission, accident and emergency attendance, and intensive therapy unit admission records, operating theatre registers and post-mortem reports. Cross-referencing with the aneurysm-screening database identified those patients who had attended screening. Previously used cost-effectiveness models were used to estimate the cost benefits to screening.

Ninety-three rAAAs occurred in men over the study period, of whom 23 (25%) had been invited for screening and 13 (14%) had accepted the invitation. All who had been screened (mean age 75 [65-82]) had abnormal aortic diameters (>30 mm) on their first scan. Of those invited, 10/23 (43%) did not attend their screening appointment, 4/23 (17%) were deemed not fit for open surgery, 4/23 (17%) ruptured whilst being assessed for aneurysm repair, 2/23 (9%) ruptured whilst under six-monthly surveillance, and 3/23 (13%) failed to attend scheduled six-monthly surveillance appointments. Reducing screened ruptures by one half could increase the cost-effectiveness of screening by 27%.

There were no failures of the screening test. The benefits of aneurysm screening can be improved by increasing the uptake of screening, the compliance with surveillance, and by streamlining the work-up process before surgery.