Prevalence and natural history of and risk factors for subaneurysmal aorta among 65-year-old men

Abstract

Background: The aims of this study were to determine the prevalence of screening-detected subaneurysmal aorta (SAA), i.e. an aortic diameter of 2.5-2.9 cm, its associated risk factors, and natural history among 65-year-old men. Methods: A total of 14,620 men had their abdominal aortas screened with ultrasound and completed a health questionnaire containing information on smoking habits and medical history. They were categorized based on the aortic diameter: normal aorta (<2.5 cm; n = 14,129), SAA (2.5-2.9 cm; n = 258), and abdominal aortic aneurysm (AAA) (≥3.0 cm; n = 233). The SAA-group was rescanned after 5 years. Associated risk factors were analyzed. Results: The SAA-prevalence was 1.9% (95% confidence interval 1.7%-2.1%), with 57.0% (50.7%-63.3%) expanding to ≥3.0 cm within 5 years. Frequency of smoking, coronary artery disease, hypertension, hyperlipidemia, and claudication were significantly higher in those with SAA and AAA compared to those with normal aortic diameter. Current smoking was the strongest risk factor for SAA (odds ratio [OR] 2.8; P < 0.001) and even stronger for AAA (OR 3.6; P < 0.001). Men with SAA expanding to AAA within 5 years presented pronounced similarities to AAA at baseline. Conclusions: Men with SAA and AAA presented marked similarities in the risk factor profile. Smoking was the strongest risk factor with an incremental association with disease severity, and disease progression. This indicates that SAA and AAA may have the same pathophysiological origin and that SAA should be considered as an early stage of aneurysm formation. Further research on the cost-effectiveness and potential benefits of surveillance as well as smoking cessation and secondary cardiovascular prevention in this subgroup is warranted.

Keywords: Abdominal aortic aneurysm; prevention and control; screening; smoking; subaneurysmal aorta; ultrasonography.

Figure 1.

Map of Sweden showing the geographical area of the four counties in middle Sweden. The uptake area comprises: (A) Uppsala, population 367,483; (B) Gävleborg, population 285,452; (C) Dalarna, population 281,046; (D) Sörmland, population 290,711. Population numbers from 2017.

Figure 2.

Infrarenal aortic diameters. Histogram presenting the distribution of the maximum infrarenal aortic diameter for the screened cohort of 65-year-old men. Embedded is a selective histogram of the size distribution of infrarenal aortic diameters ≥25 mm.

Figure 3.

Flow chart of the SAA cohort. *One man underwent elective AAA repair after 4.5 years of follow-up for a large iliac aneurysm and a 4.5-cm iAAA and was included among the attenders. AAA = abdominal aortic aneurysm; iAAA = intact abdominal aortic aneurysm.