SS10 - When to Stop: Optimizing Abdominal Aortic Aneurysm Surveillance in the Elderly

Objectives: Many older adults with asymptomatic abdominal aortic aneurysms (AAA) below the recommended intervention diameter may not benefit from life-long surveillance. This study sought to identify subgroups with a low likelihood of AAA progression to intervention diameter relative to death based on age, comorbidities, and aneurysm size.

Methods: We utilized multi-center, integrated health system aneurysm registry data from 2007-2024. Patients 65 years or older were included, and comorbidities were stratified using an internally validated risk index. AAA size at first scan was determined by ultrasound or cross-sectional imaging. Quantile regression with time-to-event analysis was utilized. The composite event included death, progression to intervention size (5cm in women, 5.5cm in men), or AAA intervention. Both the time to first event, and probability that the first event was death, rather than aneurysm progression, were determined across ages and aneurysm sizes for those with a median comorbidity score. A greater than 90% probability of death as the first event was the cutoff for surveillance cessation. This analysis was replicated for hypertensive smokers with an 85th percentile comorbidity score.

Results: A total of 10,629 patients meeting inclusion criteria were identified. The median age was 74 years; 80.3% were male. The median starting aneurysm size for both genders was 3.5cm. The 10-year mortality rate was 62%. Unadjusted, 14.6% of aneurysms 2.7-3.4cm among women reached operable size prior to death; 39.3% between 3.5-4cm; 60% between 4-4.5cm; and 79% between 4.5-5cm. For men, this was 7.9% of 2.7-3.4cm aneurysms, 59.1% of 3.5-4cm, 47.5% of 4-4.5cm, and 73.6% of >5cm. In the model, women older than 85 yrs with aneurysms smaller than 3.5cm had a ≥90% chance that their first event was death, not progression to intervention threshold; this was true for men over 80 years with aneurysms smaller than 3.5cm (Table I). In patients with higher comorbidity burdens (hypertension, smoking, the 85th percentile comorbidity score) there was ≥90% chance of death prior to reaching operative size at 75 yrs for both genders with aneurysms under 3.5cm, and 85 yrs for both genders with aneurysms under 4cm (Figure 1).

Conclusions: Surveillance can likely cease for women 85 yrs or older, or men aged 80 yrs or older, with aneurysms smaller than 3.5cm, as the chance of death prior to aneurysm progression is > 90%. Factoring in comorbidity burdens in addition to age and aortic diameter allows for more patient-specific recommendations to optimize surveillance.