Incidence, diagnosis, treatment, and outcomes of abdominal aortic aneurysms in Ontario: a retrospective cohort study

BACKGROUND: Abdominal aortic aneurysm (AAA) management substantially changed in 2003 when endovascular aneurysm repair (EVAR) became readily available in Canada. The long-term implications to routine practice in Ontario are unknown. We therefore sought to estimate trends in stable (sAAA) and ruptured (rAAA) incidence, treatment (EVAR or open surgical repair [OSR]), and postoperative mortality. METHODS: We constructed a population-based cohort study of patients with incident sAAA and rAAA in Ontario using administrative health data from April 2012 to March 2023. To assess patterns in incidence, autoregressive integrated moving average models were fit. Three population-level interventions were incorporated: a Canadian Society of Vascular Surgery (CSVS) position statement, sent to Ontario physicians in early 2018, about the Canadian AAA screening recommendations published in 2017; the COVID-19 pandemic onset in 2020; and publication of the CSVS screening guidelines for AAA in 2021. RESULTS: In total, 24 619 patients were included. Patients were predominantly male (77.2%), from urban settings (87.1%), with low comorbidity (82.3%). There was a small month-over-month increase in reported sAAA identified following the CSVS position statement in 2018. Conversely, the COVID-19 pandemic was associated with a steep drop in sAAA reported, which remained thereafter. Publication of the CSVS screening guidelines in 2021 was not associated with a change in sAAA trends. Incidence of rAAA was also reduced during the pandemic but was not affected by either publication. Treatment with EVAR for rAAA increased from 10.2% to 18%, whereas treatment with OSR declined from 40.8% to 31.3%. Untreated sAAA increased from 28.2% to 42.7%. Thirty-day (54.7%) and 1-year (61.7%) postoperative mortality from rAAA was stable, whereas mortality from sAAA increased slightly (30-d: 5% to 6.5%; 1-yr: 14% to 16.5%). CONCLUSION: Overall reporting of cases of sAAA and rAAA is decreasing in Ontario. The 2018 position statement on AAA screening guidelines led to slightly increased reported sAAA, while reporting of rAAA was not affected. As expected, the volume of patients with rAAA who received EVAR increased, while the volume of those who received OSR decreased.