AAA Screening Good for Men but Rescreening May Be Even Better

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A simple strategy of screening all men over the age of 65 for abdominal aortic aneurysm (AAA) appears to be cost effective, according to a study published online July 5, 2012, ahead of print in BMJ. Additionally, rescreening for those at risk can increase early detection, allowing for elective treatment as opposed to emergency surgery.

Researchers led by Rikke Søgaard, MSc, MPH, PhD, of the University of Southern Denmark (Odense, Denmark), used a prediction model with a hypothetical population of 100,000 men aged 65 years to test 4 different screening strategies:

• No screening
• Once per lifetime screening
• Twice per lifetime screening with a 5-year interval (for those with an aortic diameter of 25-29 mm at the initial screening)
• Lifetime screening every 5 years (for those with an aortic diameter of 25-29 mm at the initial screening)

Cost Effective, Prevents Emergency Surgeries

The model estimated a 92% probability that some form of screening would be cost effective vs. no screening, at a maximum willingness to pay threshold of £20,000 (US $31,820) per additional quality-adjusted life-year. Strategies involving either 1 or 2 screenings were both cost effective at this cutoff, whereas screening every 5 years was not (table 1).

Table 1. Cost per Quality-Adjusted Life-Year vs. No Screening

The model also predicted that while screening would lead to a 61% increase in elective surgeries (from 861 to 1,390 per 100,000), it would reduce the number of emergency surgeries by 33% (from 610 to 382 per 100,000).

If men with an aortic diameter of 25 mm to 29 mm at the initial screening were rescreened once after 5 years, 452 per 100,000 initially screened would benefit from early detection. In comparison, rescreening every 5 years for life would benefit 794 per 100,000 men. The corresponding number of acute surgeries also was further reduced with lifetime rescreening. Most of the additional clinically relevant aneurysms detected were smaller than those meeting the threshold for surgery referral. Of 1,851 men rescreened, 31 were referred to elective surgery as a consequence of one-time testing and 50 were referred as a result of testing every 5 years.

Although the model found definitively that it was cost effective to screen as opposed to not screen, the optimal choice of rescreening strategy remained uncertain.

In an e-mail communication with TCTMD, Dr. Søgaard said the take-home message of the study “is that the cost-effectiveness of one-off screening has now been confirmed even when taking into account that the prevalence is declining, the rate of incidental detection is increasing and general cardiovascular prevention has improved substantially over recent years.”

Not Without Controversy

Currently, the US Preventive Services Task Force recommends one-time screening for AAA in men aged 65 to 75 who have ever smoked. But the task force has thus far made no statement for or against screening in men who have never smoked, and advises against such screening in women. National AAA screening programs are currently being implemented in England and Scotland, but many other European countries have yet to issue guidance on the issue. According to the study authors, their findings add support to the idea of rescreening at least once.

Dr. Søgaard commented that the choice of rescreening strategy depends on how such follow-up would impact quality of life, an issue she said “we know relatively little about.” For instance, while patients with detected aneurysms eligible for referral to surgery might experience temporary anxiety that is alleviated after treatment, others with smaller aneurysms could have to wait years to be rescreened, not knowing if or when they may need treatment.

For these reasons, further research on growth and rupture rates of AAAs might help curb the uncertainty surrounding rescreening decisions. Another issue that still requires clarification concerns the screening of women. Dr. Søgaard said that while the prevalence of AAA is lower in women than in men, original research on the subject is scarce.

“We are currently conducting a second study to assess the cost-effectiveness of screening women,” she added.

Note: Costs were calculated in 2010 British pounds, which were then converted to 2012 US dollars by TCTMD staff.

 

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Source:
Søgaard R, Laustsen J, Lindholt JS. Cost effectiveness of abdominal aortic aneurysm screening and rescreening in men in a modern context: Evaluation of a hypothetical cohort using a decision analytical model. BMJ. 2012;Epub ahead of print.

 

 

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