Screening for AAA in All 65-Year-Old Men Reduces Mortality, Swedish Study Suggests


Opening the invitation to be screened for abdominal aortic aneurysms (AAA) to all 65-year-old men—and not just those deemed to be at risk—is associated with a drop in AAA-specific mortality, the first outcomes data from the Swedish national screening program show.

Moreover, although just one case was detected for every 667 men screened, the number of affected patients who had to be treated to prevent one premature death was only 1.5, Anders Wanhainen, MD, PhD (Uppsala University, Sweden), and colleagues report in a study published online September 14, 2016, ahead of print in Circulation.

“That is unique, I think,” Wanhainen told TCTMD. “That makes the screening effective almost regardless of the prevalence and also the attendance rate.”

The Swedish Program

Randomized trials have shown that screening with ultrasound followed by prophylactic surgery can reduce AAA-related mortality in selected populations. But screening practices vary in different parts of the world.

In the United States, for example, Medicare will cover a onetime ultrasound for at-risk individuals, which include those with a family history of AAA and men ages 65 to 75 who have smoked at least 100 cigarettes in their lifetime.

In Sweden, however, a screening program targeting all 65-year-old men has been gradually introduced since 2006, reaching nationwide coverage in 2015. The current analysis is the first report of outcomes data from the program.

Of 302,957 men who were invited for screening, 84% attended. That is a “really high” figure, with the nonparticipants split between those who simply choose not to get screened and those who have medical issues that prevent them from participating in anything, Wanhainen said.

AAA was detected in 1.5% of men. Of those, 29% underwent a prophylactic intervention during a mean follow-up of 4.5 years. The mortality rate within 30 days of the procedure was lower for endovascular versus open repair (0.3% vs 1.3%; P < 0.001).

There was a significant 4% reduction in AAA-specific mortality per year of screening (P = 0.02). From 2000, before screening was introduced, to 2014, the rate of AAA-specific mortality declined from 74 to 45 per 100,000. The reductions were greater in counties that had been screening for a longer period of time.

The investigators estimated that across Sweden, which has a total population of about 9.5 million, the screening program prevents about 90 premature deaths from AAA each year and leads to a gain of 577 quality-adjusted life-years (QALYs).

The incremental cost-efficiency ratio—a measure of cost-effectiveness—was estimated to be €7,770 per QALY.

This first evaluation of the Swedish nationwide AAA screening program indicates that a population-based AAA screening program can be implemented in a simple way, at low cost, and that it is well accepted by the population,” the authors write.

‘A Reason for More Countries to Join’

Wanhainen et al acknowledge that the decline in AAA-specific mortality could have been due to other causes aside from the screening program, including the falling prevalence of disease, growing use of endovascular repair, better perioperative outcomes, and a trend toward increasing life expectancy.

To TCTMD, however, Wanhainen said that he’s confident the reduction can be attributed to the screening program because similar substantial declines were not seen for mortality stemming from all causes, ischemic heart disease, or cancer during the same time period.

There are potential downsides to widespread screening for AAA, such as the distress of knowing about a disease and the small risks of mortality and morbidity from prophylactic treatment, he said, “but compared to all the lives we save, the net effect is very, very positive.”

“Screening in the current setting with a very low prevalence compared to historical data in the endovascular era is very effective, very cost-effective,” Wanhainen said. “It’s a reason for more countries to join.”

While screening might have to become more selective if the prevalence of AAA continues to fall, “for the moment, it is very effective to invite all men,” he noted.

The more selective screening used in the United States is “not a bad strategy with a lower prevalence,” he said. “It’s okay, but you do miss a few men who have never smoked and they are even healthier and have a longer life to be saved. So that’s the mathematics behind inviting everyone.”


 

 

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Sources
  • Wanhainen A, Hultgren R, Linné A, et al. Outcome of the Swedish nationwide abdominal aortic aneurysm screening program. Circulation. 2016;Epub ahead of print.

Disclosures
  • Wanhainen reports no relevant conflicts of interest.

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