Patrik Söderberg: Abdominal Aortic Aneurysm in the Era of Declining Prevalence - Aspects of Screening

Abstract

Introduction: Abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta associated with risk of rupture and high mortality. Population-based screening programs for older men have been implemented in several countries, including Sweden, and have reduced AAA-related mortality. However, AAA epidemiology has changed in recent decades, with a marked decline in prevalence. Important knowledge gaps remain regarding the natural history of AAA and sub-aneurysmal aortic aneurysm (SAAA) in women, the long-term outcome of current screening programs in men, and optimal screening strategies in low-prevalence populations.

Aim: This thesis aimed to improve understanding of AAA and SAAA in women, to evaluate the current screening program in men, and to assess the potential role of risk-stratified screening approaches in both men and women.

Methods: The thesis comprises four studies. Study I investigated the five-year natural history of screening-detected SAAA and AAA in 70-year-old women and included a systematic review of AAA repair. Study II evaluated risk factor–based targeted screening strategies for AAA in 65-year-old men using Swedish screening data. Study III assessed the feasibility and outcomes of targeted screening among 70-year-old women with a history of smoking. Study IV examined the long-term outcome of the Swedish nationwide AAA screening program in 65-year-old men using screening and mortality registry data.

Results: Among women with SAAA at age 70, nearly half progressed to AAA within five years, and one-third of those with AAA underwent elective repair. In men, targeted screening based on smoking history identified most AAAs while reducing the number invited. In women, targeted screening of smokers doubled the prevalence of detected AAAs compared with general screening. Screening in men was associated with a 46% reduction in rupture-related mortality.

Conclusion: Population-based AAA screening reduces rupture-related mortality even in low-prevalence settings. Improved understanding of aneurysm disease and the ability to identify high-risk individuals support risk factor–based screening as a complementary strategy in both men and women.