Repeat AAA Screens Found Cost-Effective

Repeat screening for men at high risk of an abdominal aortic aneurysm appears to be cost-effective, Danish researchers reported.
A mathematical modeling study confirmed that one-time screening of men 65 and older was cost-effective – a finding that has already led to screening programs in England and Scotland, according to Rikke Søgaard, PhD, of the University of Southern Denmark in Odense, Denmark, and colleagues.
But the study also suggested that rescreening high-risk men at least once would also save money, Søgaard and colleagues reported online in BMJ.
The findings apply directly only to countries with a national health service and details of the costs – and therefore cost-effectiveness -- may vary from place to place, the authors cautioned.
And the study, based on a hypothetical cohort of 100,000 men, leaves some other questions open: "The optimal choice of rescreening strategy appears to be uncertain, and further research is needed to establish the long-term costs and benefits of rescreening," Søgaard and colleagues concluded.
Follow-up of randomized trials has shown that screening in men older than 65 cuts the risk of death from abdominal aortic aneurysm by about half, the researchers noted.
But it has not been clear if there is additional benefit in continuing to screen men, especially given advances in primary and secondary prevention of cardiovascular disease and increasing use of such techniques as ultrasound, which can increase incidental detection of aneurysms.
To investigate the issue, Søgaard and colleagues constructed a mathematical prediction model to test four approaches: no screening, a single screening at age 65, two lifetime screenings 5 years apart with the first at 65, and screening every five years starting at 65.
The model required data on such things as prevalence, rupture rates, and mortality rates after rupture and surgical treatment, which the researchers obtained by analyzing research registries from two Danish screening trials, the Danish vascular registry, and national registries for causes of death.
In the model, high rupture risk was defined as an aortic diameter of 25 through 29 millimeters, and aneurysm was defined as a diameter of 30 millimeters or more.
The model suggested:

• There is a 92% probability that some form of screening would be cost-effective at a threshold of about $31,460.
• Assuming incidental detection was zero in small aneurysms and 12% annually in aneurysms of at least 55 millimeters, 2,469 men per 100,000 given an initial screen at age 65 would be found to have a clinically relevant aneurysm.
• If men with a high rupture risk were rescreened once after 5 years, 452 additional men per 100,000 initially screened would benefit from early detection at a cost of about $15,537 per quality-adjusted life year.
• Lifetime rescreening every 5 years would detect 794 additional men per 100,000 of those initially screened, at a cost of about $46,046 per quality-adjusted life year.

Regarding the two rescreening strategies, the number of elective operations to repair an aneurysm was estimated to increase from 861 per 100,000 with no screening, to 1,390 if screening were done once, and then to 1,496 if screening was repeated after 5 years, and 1,530 per 100,000 if screening occurred at 5-year intervals.
On the other hand, the researchers estimated the number of emergency operations would fall from 610 per 100,000 with no screening to 382 for screening once, and then to 363 and 360 per 100,000 for one-time repeat screening and 5-year screening, respectively.
At the same time, the aneurysm-related death rate would fall from 788 to 520 and 511 per 100,000 for one-time repeat screening and 5-year screening, respectively.
One major limitation of the study is its possible lack of generalizability to less homogeneous populations and to countries without national health insurance, since costs -- especially of surgery -- may differ. The investigators did note, however, that emergency surgery is usually more expensive than elective surgery so that cost savings could result from fewer emergency repairs, regardless of overall surgical costs.