AAA Repair Size Thresholds Used in Contemporary Practice Warrant Revision

Contemporary abdominal aortic aneurysm (AAA) rupture rates endorsed by the Society for Vascular Surgery are lower than historical benchmarks. This may have implications for AAA care. Our objective was to use Society for Vascular Surgery-endorsed AAA rupture rates to inform optimal size thresholds for repair. We used Markov modeling to estimate life expectancy for patients with AAAs. The primary outcome was mortality. We estimated survival using Social Security Administration life tables and modified them with published contemporary AAA rupture estimates. For those undergoing repair, we further modified estimates with data on complications, late rupture, open conversion, and survival from the Vascular Quality Initiative and Medicare. We used this model to estimate life expectancy for 60-year-old men and women with AAAs who were repaired at sizes between 5.0 and 7.5 cm. The annual risk of death under surveillance for a 60-year-old woman presenting with a 5.0-cm AAA using repair thresholds of 5.5 cm, 6.0 cm, 6.5 cm, and 7.0 cm, was 1.7%, 2.3%, 2.7%, and 2.8%, respectively. The corresponding risk for a man was 2.3%, 2.9%, 3.3%, and 3.4%. Consequently, the repair threshold conferring the greatest life expectancy for a 60-year-old woman presenting with a 5.0 cm AAA was 5.8 cm (Fig). Survival varied by <1 month for thresholds between 5.4 and 6.2cm, indicating that repair for AAAs within this range maximized survival. The optimal repair threshold for a 60-year-old man presenting with a 5.0 cm AAA was 6.0 cm. Again, survival varied by <1 month for thresholds between 5.4 and 6.1cm. Notably, women at increased cardiac risk had a higher optimal repair threshold at 6.2 cm, and the range of thresholds that maximized survival spanned from 6.0 to 7.1 cm. Similarly, men at increased cardiac risk had an optimal repair threshold of 6.8 cm, with a range of 6.3 to 7.3cm. The optimal threshold for AAA repair is more nuanced than a discrete size. Specifically, there appears to be a range of sizes for which repair is reasonable to maximize survival, and all are higher than current guidelines. These findings suggest that contemporary AAA size thresholds for repair should be revised.