Screening for Abdominal Aortic Aneurysm—A Call to Arms?

The goal of abdominal aortic aneurysm (AAA) detection is to identify asymptomatic AAA before rupture, as the mortality rate associated with a ruptured aneurysm may exceed 80%, while the mortality rate of an elective repair is 0.5% to 4% in most contemporary studies. The US Preventive Services Task Force (USPSTF) has recommend 1-time screening for patients at risk of AAA since 2005, and AAA screening has been a covered benefit under Centers for Medicare & Medicaid Services since 2007. The 2019 update by USPSTF^1,2 has incorporated new evidence since its last update in 2014 and continues to recommend 1-time screening for certain patients.

In the United States, AAA screening continues to be underused even for patients who meet the established criteria for screening,³ and the contemporary prevalence of AAA is unknown.⁴ Barriers to screening may include gaps in patient or physician education, poor access to testing, or unwillingness of patients to undergo testing once offered. Two 2012 commentaries^5,6 based on alternative interpretations of available data and anecdotal experiences suggested that the USPSTF should reconsider the value of AAA screening. Since then, the USPSTF has incorporated new evidence into updated guidelines in 2014⁴ and again in 2019,^1,2 validating its previous recommendations for screening similar at-risk populations as defined in previous versions.

The 2019 recommendations are complicated. Specifically, the 2019 USPSTF statement recommends 1-time screening for AAA with ultrasonography for men aged 65 to 75 years who have ever smoked (Grade B recommendation) and selective screening for men aged 65 to 75 years who have never smoked (Grade C recommendation). For women aged 65 to 75 years who have ever smoked or have a family history of AAA, the USPSTF indicates that “the current evidence is insufficient to assess the balance of benefits and harms of screening for AAA”² (Grade I statement), and the USPSTF recommends against routine screening for women who have never smoked and have no family history of AAA (Grade D recommendation).

While the overall prevalence of AAA has decreased in many Western countries, the individual prospect of having an AAA for a person at risk remains the same. Major risks include male sex, smoking history, cumulative smoking burden, and family history of AAA. Patients who meet criteria should be offered a screening ultrasonographic test, as this test is safe, accurate, and has been shown to decrease aneurysm-related mortality and perhaps reduce all-cause mortality. Appropriate screening has been estimated to gain a mean of 131 life-years per 1000 persons screened for AAA. This advantage compares favorably with the Grade B USPSTF recommendation for breast cancer screening, which yields 95 to 128 life-years per 1000 women screened.⁷

Many patients are found incidentally to have an AAA when imaging is performed for other reasons or by non–primary care physicians.⁸ Patients who do not meet the threshold for repair should receive routine ultrasound surveillance based on established guidelines.⁹ This circumstance poses a challenge to receiving appropriate care, as only half of imaging tests are ordered by a primary care physician,⁸ and gaps in surveillance may increase the likelihood of rupture nearly 6-fold.¹⁰

One of the key unresolved discrepancies between AAA screening and AAA mortality is that 41% of AAA-related deaths are among women and 22% of AAA-related deaths are among nonsmokers, neither of whom would have qualified for screening, although the Grade I recommendation for women aged 65 to 75 years who have ever smoked or who have family history of AAA suggest there is simply insufficient evidence to make a recommendation, and the Grade C recommendation for men aged 65 to 75 years who have never smoked indicates clinicians should consider the benefits and harms in advising patients.¹¹ Additionally, repair of AAA has become more common in patients older than 80 years. It is unknown if this increase is associated with successful screening and surveillance when these patients were younger, serendipitous diagnosis and treatment for patients who were not screened and otherwise would have had AAA repaired when they were younger, or advances in endovascular techniques that have allowed for repair in patients who were not candidates for open surgical procedures or endovascular repair with older technology. Patients in this age cohort may have met criteria but not have undergone screening at the recommend age of 65 to 75 years, and they may be at increased risk with advancing age. Therefore, it may be beneficial to consider screening these patients if their overall health would otherwise qualify them to receive repair.

The updated USPSTF AAA recommendations^1,2 acknowledge the insufficient evidence to make a screening recommendation for women with a smoking history. This is in part owing to the lower prevalence of AAA among women.¹¹ Complicating the decision-making process is that, while women tend to rupture aneurysms at a smaller diameter, they also have higher mortality with elective repair. The USPSTF considers evidence insufficient to make a determining recommendation^1,2; however, these challenges have led the Society for Vascular Surgery⁹ to recommend more liberal use of screening, recommending 1-time ultrasonographic screening for AAA in men and women aged 65 to 75 years with a history of tobacco use, men 55 years or older with a family history of AAA, and women aged 65 years with a family history of AAA. Women with a significant smoking history may have a prevalence of AAA exceeding 2%; therefore, it is reasonable to screen this cohort for AAA and consider repair for an AAA greater than 5.0 to 5.5 cm in diameter.

The most effective way to prevent death from ruptured AAA is to prevent rupture. More research is needed to optimize diffusion of current recommendations and to identify other patient cohorts with a high pretest probability of AAA and who benefit from repair and therefore screening.

Published: December 10, 2019. doi:10.1001/jamanetworkopen.2019.17168

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2019 Mell M. JAMA Network Open.

Corresponding Author: Matthew Mell, MD, MS, Division of Vascular Surgery, University of California, Davis, 2335 Stockton Blvd, NAOB5017, Sacramento, CA 95817 (mwmell@ucdavis.edu).

Conflict of Interest Disclosures: None reported.