Trends in Abdominal Aortic Aneurysm Repair Incidence, Comorbidity, Treatment, and Mortality: A Danish Nationwide Cohort Study, 1996-2018

Background: Significant changes in Western populations' abdominal aortic aneurysm (AAA) epidemiology have been reported following the introduction of screening, endovascular AAA repair, and reduced tobacco consumption. We report incidence and mortality of AAA repair in Denmark from 1996 to 2018, where AAA screening was not implemented.

Methods: Nationwide cohort study of prospective data from population-based Danish registries covering 1996 to 2018. We identified 15,395 patients undergoing first-time AAA repair using the Danish Vascular Registry. Comorbidity was assessed by Charlson's Comorbidity Index (CCI). Incidence rate (IR) ratios and mortality rate ratios (MRR) were estimated by multivariable Poisson and Cox regression, respectively.

Results: Overall AAA repair IR decreased by 24% from 1996 through 2018, mainly reflecting a 53% IR reduction in ruptured AAA repairs in men. Overall, the IR decreased 52-63% in age groups below 70 years and increased 81% among octogenarians. The proportion of intact AAAs repaired endovascularly increased from 2% in 1996-1999 to 42% in 2015-2018. For both ruptured and intact AAAs the CCI score increased by 0.9% annually independently of age and sex. The adjusted five-year MRR in 2016-2018 vs.1996-2000 was 0.46 (95% confidence interval (CI): 0.39-0.54) following ruptured and 0.51 (95% CI: 0.44-0.59) following intact AAA repair.

Conclusion: In Denmark, overall AAA repair incidence decreased between 1996 and 2018, primarily reflecting a reduction among males and a shift to an older population requiring intervention. These trends mirror changes in tobacco consumption in Denmark. Regardless of age and comorbidity, AAA repair mortality decreased markedly during the study period.