Screening for abdominal aortic aneurysm reduces long term mortality
Screening for abdominal aortic aneurysm has been shown to reduce the short-term mortality associated with this condition. A large study has now demonstrated that the benefits are maintained for up to ten years.
The Multicentre Aneurysm Screening Study (MASS) randomised 67, 770 men aged 65-74 to either ultrasound screening or no screening. Four centres were involved in the project and screening and surveillance was mostly delivered in a primary care setting.
If an aneurysm was detected, defined as a diameter >3cm, then appropriate follow-up was instigated either annually (3.0-4.4 cm) or 3 monthly (4.5-5.4 cm). Surgery was offered when the aneurysm reached 5.5 cm, had grown by greater than 1 cm in the past year or was associated with symptoms. Trial participants were followed up for ten years. The primary outcomes were mortality, costs related to aneurysm and cost per life year gained.
In the screened group, there were 155 deaths related to abdominal aortic aneurysm over the ten-year follow-up period and 296 in the control group (relative risk reduction 48%, 95% CI 37-57%).
Cost-effectiveness analysis showed the cost per man invited to screening was £100 (95% CI, £82-£118). This translated into a cost-effectiveness ratio of £7,600 (£5,100 -£13,000) per life year gained. Importantly, the degree of benefit seen in the earlier years of follow-up was maintained in later years.
The investigators did note that the incidence of ruptured abdominal aortic aneurysm in those originally screened as normal increased markedly eight years from the original screening ultrasound.
Screening for abdominal aortic aneurysm would appear to reduce the mortality associated with this condition and this benefit is maintained up to ten years. Indeed a national screening programme could halve the number of aneurysm-related deaths. Furthermore, this is a cost-effective process but as with any screening programme the acceptability of the test, quality of follow-up and the availability of timely effective interventions are the key to ongoing success.
Thompson SG, Ashton HA, Gao L et al. Screening men for abdominal aortic aneurysm: 10-year mortality and cost effectiveness results from the randomised Multicentre Aneurysm Screening Study. BMJ 2009; 338: b2307 doi:10.1136/bmj.b2307Reviewer
Dr Peter Savill
GPwSI Cardiology, Southampton