Screening for abdominal aortic aneurysm (AAA) reduces risk of rupture, aneurysm-related- and all-cause mortality (1-3). The European Society for Vascular Surgery (ESVS) recommends one-time screening of all men at the age of 65 years, and repeated imaging after five to ten years for individuals with an aortic diameter (AD) of 25-29 mm (4). The Department of Vascular Surgery at Oslo University Hospital (OUH) initiated a AAA screening program in May 2011, where all 65-year-old men with home address in Oslo are invited. The aim of the present study was to evaluate the impacts of the screening program. The primary goal was to examine the total rupture rate in the population eligible for AAA screening and in the actual screened population. The secondary goal was to examine all-cause mortality comparing three groups: AD < 25 mm, AD 25-29 mm and AD ≥ 30 mm.

Participants screened between May 2011 and September 2019 were included in the study. Of 12810 screened participants during this period, 90.7% (n=11618) had an AD < 25 mm, 6.7% (n=862) had an AD of 25-29 mm, and 2.6 % (n=330) had an AD ≥ 30 mm, defined as AAA (5). All participants with AAA (n=330), and a randomized selection of an equal number of participants from the two other groups were included, resulting in 990 participants included in the final analysis. Follow-up data were retrospectively collected through electronic patient charts, with maximum follow-up until April 2022. To examine the total rupture rate in the population eligible for screening, all individuals admitted to OUH with a ruptured AAA (rAAA) during the screening period were identified using the International Classification of Diseases 10 (ICD-10) code I70.3 (rAAA). This list was cross-checked with the list of screened participants. Descriptive analysis and survival analysis were performed with Stata/SE (ver. 17.0). The Log-rank test was used to test for difference between groups, and the significance level was set to p<0.05.

Among the 660 screened participants with AD ≥ 25 mm, 0.45% (n=3) ruptured during the follow-up period: two in the AAA group and one in the AD 25-29 mm group. In addition, 156 non-screened individuals were admitted to OUH with rAAA. Of these, 3.2% (n=5) were eligible for screening (Figure 1). Crosschecking these five individuals with the screening program, we found that three were invited, but did not attend or cancelled their appointment. There was no record of the last two being invited to the screening program. Among the 156 non-screened individuals with rAAA, 34.6% (n=54) had previously been diagnosed with AAA outside the screening program. The surveillance statuses of these individuals are shown in Table 1. In the group of participants with an AD of 25-29 mm, 22.4% (n=74) had repeated imaging of the abdominal aorta at OUH after the initial screening (median 4.9 years, IQR 3.75 years). Of these, 33.8% (n=25) developed AAA, of which 16% (n=4) were repaired, and one individual was found unsuited for treatment due to high age and comorbidities. There was a significantly higher all-cause mortality in the AAA group compared to the two other groups (p<0.05), but this was not the case when comparing the AD 25-29 mm group to the AD < 25 mm group (p=0.4) (Figure 2). The all-cause mortality was 14.8% (n=49) in the AAA group, 6.4% (n=21) in the AD 25-29 mm group, and 5.2% (n=17) in the AD <25 mm group. The median follow-up time was 7.1 years, 95% CI [6.84, 7.22].

The total rupture rate in the screened population was 0.45%. Of non-screened individuals with rAAA, 1.9% had been invited to screening, but had declined their invitation. Interestingly, 34.6% of the non-screened ruptures had known AAAs and 18.5% of these were lost to follow-up. This indicates a potential area of improvement regarding follow-up of patients with AAAs detected outside the screening program. Finally, we also found a significantly higher all-cause mortality for participants with AAA, compared to participants with AD < 30 mm.

1. Cosford PA, Leng GC. Screening for abdominal aortic aneurysm. Cochrane Database Syst Rev. 2007(2):Cd002945. 2. Ali MU, Fitzpatrick-Lewis D, Miller J, Warren R, Kenny M, Sherifali D, et al. Screening for abdominal aortic aneurysm in asymptomatic adults. J Vasc Surg. 2016;64(6):1855-68. 3. Takagi H, Ando T, Umemoto T. Abdominal Aortic Aneurysm Screening Reduces All-Cause Mortality: Make Screening Great Again. Angiology. 2018;69(3):205-11. 4. Wanhainen A, Verzini F, Van Herzeele I, Allaire E, Bown M, Cohnert T, et al. Editor's Choice - European Society for Vascular Surgery (ESVS) 2019 Clinical Practice Guidelines on the Management of Abdominal Aorto-iliac Artery Aneurysms. Eur J Vasc Endovasc Surg. 2019;57(1):8-93. 5. Rabben T, Mansoor SM, Bay D, Sundhagen JO, Guevara C, Jorgensen JJ. Screening for Abdominal Aortic Aneurysms and Risk Factors in 65-Year-Old Men in Oslo, Norway. Vasc Health Risk Manag. 2021;17:561-70.