Evaluating the cost-effectiveness of changes to the surveillance intervals in the UK abdominal aortic aneurysm screening programme
Publication: Science Direct
Michael J. Sweeting, John Marshall, Matthew Glover, Akhtar Nasim, Matthew J. Bown
25 December 2020
The National Health Service Abdominal Aortic Aneurysm Screening Programme has been shown to be highly cost-effective. Recently, the prevalence of screen-detected abdominal aortic aneurysm (AAA) has fallen. If this trend continues, the cost-effectiveness of AAA screening is threatened.
One option to improve program cost-effectiveness is to extend the length of time between surveillance scans for men who are found to have AAA at screening. The potential safety and cost savings associated with such a change are unknown.
Extending the length of time between surveillance scans for men with screen-detected AAA in the Abdominal Aortic Aneurysm Screening Programme, especially for those with smaller AAAs, reduces the incremental cost per quality-adjusted life-year of the program. This is associated with a small increase in the number of adverse clinical events in the overall population of men invited for screening.
It is unclear whether the benefit of cost saving from refining surveillance strategies justifies the increased harms associated with such a change in clinical practice. Furthermore, realizing the benefits of minimized surveillance strategies for individual screening units may be difficult owing to the regional structure of the AAA screening workforce.
This study aimed to investigate the safety and cost-effectiveness of lengthening the time between surveillance ultrasound scans in the UK Abdominal Aortic Aneurysm (AAA) Screening Programme.
A discrete event simulation model was used to evaluate the cost-effectiveness of AAA screening for men aged 65, comparing current surveillance intervals to 6 alternative surveillance interval strategies that lengthened the time between surveillance scans for 1 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%.
Compared with 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 (3.0-3.9 cm) 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.
Lengthening surveillance intervals in the UK Abdominal Aortic Aneurysm Screening Programme, especially for small AAA, can marginally reduce the incremental cost per QALY of the program. Nevertheless, whether the cost savings from refining surveillance strategies justifies a change in clinical practice is unclear.
