Aspects of subaneurysmal aortas in a screening setting

With the introduction of screening programmes for abdominal aortic aneurysm (AAA) more individuals are being identified with a subaneurymal aorta (SAA; diameter 25-29mm). More recent data indicate that these aortas may not be as harmless as previously thought, but there is, however, no general agreement on how SAA should be managed. The aims of this thesis were to study men with screening detected SAA, regarding: (I) prevalence, risk factors and comorbidities; (II), the long-term natural course regarding development to AAA ≥30mm, in particular the progression to AAA ≥55mm, to assess the AAA repair rate, turn down, and mortality rates; (III) the association between aortic morphological baseline factors; (SAA diameter, aortic index related to height and body surface area as well as relative aortic diameter to proximal aorta) and the risk for later progression to AAA ≥55mm; and (IV) describe health utility (HU) values and compare them in men with screened AAA, SAA and in men with normal aortic diameters. There was a marked similarity in the risk factor profile between men with SAA representing 2% of the screening population and men with AAA with smoking as the most important risk factor, with an incremental association between smoking and disease severity. Most SAAs eventually progress to an AAA ≥30mm, of which 30% eventually reach the threshold for AAA-repair within 10 years. A follow-up policy with an ultrasound scan after five years can safe and effectively identify those at risk of developing clinically relevant AAAs, and should be considered for anyone with reasonably good life expectancy. Baseline SAA diameter, aortic size index, and aortic height index were all independently associated with progression to AAA ≥55mm, with aortic size index as the strongest predictor, whereas relative aortic diameter was not. These morphological factors may be considered for stratification of follow-up at initial screening. At baseline screening, HUs were similar between men with AAA, SAA, and normal aortas. Compared to SAAs and controls, lower health utility scores were observed in men with AAA after five years, most likely associated with higher frequency of smoking and comorbidities. 

Aspects of subaneurysmal aortas in a screening setting

With the introduction of screening programmes for abdominal aortic aneurysm (AAA) more individuals are being identified with a subaneurymal aorta (SAA; diameter 25-29mm). More recent data indicate that these aortas may not be as harmless as previously thought, but there is, however, no general agreement on how SAA should be managed. The aims of this thesis were to study men with screening detected SAA, regarding: (I) prevalence, risk factors and comorbidities; (II), the long-term natural course regarding development to AAA ≥30mm, in particular the progression to AAA ≥55mm, to assess the AAA repair rate, turn down, and mortality rates; (III) the association between aortic morphological baseline factors; (SAA diameter, aortic index related to height and body surface area as well as relative aortic diameter to proximal aorta) and the risk for later progression to AAA ≥55mm; and (IV) describe health utility (HU) values and compare them in men with screened AAA, SAA and in men with normal aortic diameters. There was a marked similarity in the risk factor profile between men with SAA representing 2% of the screening population and men with AAA with smoking as the most important risk factor, with an incremental association between smoking and disease severity. Most SAAs eventually progress to an AAA ≥30mm, of which 30% eventually reach the threshold for AAA-repair within 10 years. A follow-up policy with an ultrasound scan after five years can safe and effectively identify those at risk of developing clinically relevant AAAs, and should be considered for anyone with reasonably good life expectancy. Baseline SAA diameter, aortic size index, and aortic height index were all independently associated with progression to AAA ≥55mm, with aortic size index as the strongest predictor, whereas relative aortic diameter was not. These morphological factors may be considered for stratification of follow-up at initial screening. At baseline screening, HUs were similar between men with AAA, SAA, and normal aortas. Compared to SAAs and controls, lower health utility scores were observed in men with AAA after five years, most likely associated with higher frequency of smoking and comorbidities. 

Morphological factors associated with progression of subaneurysmal aortas

Background: The aim of this population-based cohort study was to assess the association between aortic morphological baseline factors in 65-year-old men with subaneurysmal aortic diameter (25-29 mm) and risk of later progression to abdominal aortic aneurysm (AAA) generally considered to be at a diameter for repair (at least 55 mm). Methods: Men with a screening-detected subaneurysmal aorta between 2006 and 2015 in mid-Sweden were re-examined using ultrasonography after 5 and 10 years. Cut-off values for baseline subaneurysmal aortic diameter, aortic size index, aortic height index, and relative aortic diameter (with respect to proximal aorta) were analysed using receiver operating characteristic (ROC) curves, and their associations with progression to AAA diameter at least 55 mm evaluated by means of Kaplan-Meier curves and a multivariable Cox proportional hazard analysis adjusted for traditional risk factors. Results: Some 941 men with a subaneurysmal aorta and median follow-up of 6.6 years were identified. The cumulative incidence of AAA diameter at least 55 mm at 10.5 years was 28.5 per cent for an aortic size index of 13.0 mm/m2 or more (representing 45.2 per cent of the population) versus 1.1 per cent for an aortic size index of less than 13.0 mm/m2 (HR 9.1, 95 per cent c.i. 3.62 to 22.85); 25.8 per cent for an aortic height index of at least 14.6 mm/m (58.0 per cent of the population) versus 2.0 per cent for an aortic height index of less than 14.6 mm/m (HR 5.2, 2.23 to 12.12); and 20.7 per cent for subaneurysmal aortic diameter 26 mm or greater (73.6 per cent of the population) versus 1.0 per cent for a diameter of less than 26 mm (HR 5.9, 1.84 to 18.95). Relative aortic diameter quotient (HR 1.2, 0.54 to 2.63) and difference (HR 1.3, 0.57 to 3.12) showed no association with development of AAA of 55 mm or greater. Conclusion: Baseline subaneurysmal aortic diameter, aortic size index, and aortic height index were all independently associated with progression to AAA at least 55 mm, with aortic size index as the strongest predictor, whereas relative aortic diameter was not. These morphological factors may be considered for stratification of follow-up at initial screening