Study of Modern AAA Metrics Supports Expansion of Current Screening Guidelines

September 2, 2021—The Society for Vascular Surgery (SVS) announced the publication of results of a database review of more than 500,000 abdominal aortic aneurysm (AAA) repairs that revealed the majority of patients treated for rupture did not meet the criteria for aneurysm screening.

The investigators, who are from Beth Israel Deaconess Medical Center in Boston, Massachusetts, concluded that most patients who had undergone repair for ruptured AAAs did not qualify for screening and that EVAR was the primary treatment of both ruptured and intact AAAs with relatively low in-hospital mortality. Based on these findings, the investigators suggested that expansion of the screening criteria to include selected women and a wider age range should be considered, noted the SVS announcement.

The findings were published by Kirsten D. Dansey, MD, et al in Journal of Vascular Surgery (2021;74:414-424).

"Although the screening policy has likely contributed to the decrease in the incidence of ruptured AAAs, the proportion of ruptured AAAs occurring in patients currently excluded from screening is unknown," commented Dr. Dansey in the SVS press release. "Our aim in this study was to identify the proportion of patients who had presented for AAA repair but were not eligible for screening."

The goal of screening is to identify people at risk of AAA and treat it before rupture, greatly improving patient survival. AAA remains the 15th leading cause of death in the United States, and the associated risk for death with rupture remains high, despite the introduction of endovascular abdominal aortic aneurysm repair (EVAR), noted the society.

As summarized in the announcement, the investigators used the National Inpatient Sample from 2004 to 2015 to identify ruptured and intact AAA admissions and repairs by the International Classification of Diseases codes. They evaluated 65,125 admissions for ruptured AAAs and 461,191 repairs for intact AAAs.

Current US Preventative Task Force screening criteria for AAA includes males between the ages 65 and 75 years with a history of smoking.

The investigators found that those who did not meet the criteria for screening included:

• 68% of all patients admitted for AAAs
• 59% of patients who had undergone repair for ruptured AAAs

Of those patients who did not qualify for screening:

• 63% were aged > 75 years
• 24% were aged < 65 years
• 36% were women

During the study period, EVAR increased for ruptured AAA from 10% to 55% with a mortality of 35%. EVAR for intact AAAs increased from 45% to 83% with a mortality of 2%.

The investigators noted that the United Kingdom’s National Institute for Health and Care Excellence (NICE) guidelines for AAA diagnosis and management found benefit for AAA screening for a prevalence as low as 0.35%.

"The current screening guidelines are not based on modern practice data," Dr. Dansey stated in the announcement. "The advantage of using EVAR is missed when calculating which patients would benefit from this low-risk procedure. Patients aged > 75 years constituted more than one half of the patients admitted with AAA rupture and represent a critical and increasing screening-ineligible population. This population will realize an especially high benefit of undergoing repair on intact AAAs, given the difference in mortality of 45% after repair of rupture AAAs vs 1.3% after repair of intact AAAs."

Dr. Dansey continued, "It would be reasonable to conclude that screening women, who have a prevalence of AAA of 1.7% (reported for women with a positive smoking history) would be cost-effective, as was recommended in the NICE guidelines."

She added, "The number of ruptured AAA admission has decreased over time, suggesting that screening and implementation of EVAR have had a positive effect. However, the number of repairs for rupture AAAs has remained unchanged, suggesting that screening remains underutilized."