Objectives: To investigate the safety and cost-effectiveness of lengthening the time between surveillance ultrasound scans in the UK Abdominal Aortic Aneurysm (AAA) screening programme.

Methods: A discrete event simulation model was used to evaluate the cost-effectiveness of AAA screening for men aged 65, comparing current surveillance intervals to six alternative surveillance interval strategies that lengthened the time between surveillance scans for one or more AAA size categories. The model considered clinical events and costs incurred over a 30-year time horizon and the cost per quality-adjusted life-year (QALY). The model adopted the National Health Service perspective and discounted future costs and benefits at 3.5%.

Results: Compared to current practice, alternative surveillance strategies resulted in up to a 4% reduction in the number of elective AAA repairs but with an increase of up to 1.6% in the number of AAA ruptures and AAA-related deaths. Alternative strategies resulted in a small reduction in QALYs compared to current practice but with reduced costs. Two strategies that lengthened surveillance intervals in only very small AAAs (3.0-3.9cm) provided, at a cost-effectiveness threshold of £20,000 per QALY, the highest positive incremental net benefit. There was negligible chance that current practice is the most cost-effective strategy at any threshold below £40,000 per QALY.

Conclusions: Lengthening surveillance intervals in the UK AAA screening programme, especially for small AAA, can marginally reduce the incremental cost per QALY of the programme. However, whether the cost saving from refining surveillance strategies justifies a change in clinical practice is unclear.