From the Guidelines
The annual rupture rate of abdominal aortic aneurysm (AAA) is approximately 9% for AAAs of 5.5 to 5.9 cm, 10% for AAAs of 6.0 to 6.9 cm, and 33% for AAAs of 7.0 cm or more, as reported in a study published in the Annals of Internal Medicine 1. The annual rupture risk for abdominal aortic aneurysms (AAAs) varies based on aneurysm size.
- For small AAAs (less than 5.5 cm in diameter), the annual rupture risk is generally lower, but exact percentages are not provided in the study 1.
- For large AAAs (5.5 cm or greater in diameter), the annual rupture risk increases significantly, with reported rates of:
- 9% for AAAs of 5.5 to 5.9 cm
- 10% for AAAs of 6.0 to 6.9 cm
- 33% for AAAs of 7.0 cm or more These percentages highlight the importance of monitoring aneurysm size and growth rate, as well as managing risk factors such as smoking and hypertension, to reduce the risk of rupture 1. Regular monitoring through ultrasound or CT scans is crucial for patients with known AAAs, and surgical intervention is typically recommended when the aneurysm reaches a certain size or if rapid growth is observed. Understanding these risks helps guide management decisions, balancing the risk of rupture against the risks associated with surgical repair, as noted in the study published in the Annals of Internal Medicine 1.
From the Research
Annual Rupture Rate of Abdominal Aortic Aneurysm (AAA)
The annual rupture rate of abdominal aortic aneurysm (AAA) varies based on the size of the aneurysm and the patient's gender.
- For small AAAs (3.0 to 4.4 cm), the maximum potential rupture rate is 2.1% per year 2.
- For aneurysms of 4.5 to 5.9 cm, the equivalent rate is 10.2% per year 2.
- The actual rupture rate for aneurysms up to 5.9 cm is 0.8% per year 2.
- For aneurysms of 5.0 to 5.9 cm, the average risk of rupture is 1.0% per year in male patients and 3.9% per year in female patients 3.
- For aneurysms of 6.0 cm or greater, the average risk of rupture is 14.1% per year in male patients and 22.3% per year in female patients 3.
- The 1-year incidence of probable rupture by initial AAA diameter is 9.4% for AAA of 5.5 to 5.9 cm, 10.2% for AAA of 6.0 to 6.9 cm, and 32.5% for AAA of 7.0 cm or more 4.
Factors Affecting Rupture Rate
Several factors can affect the rupture rate of AAA, including:
- Aneurysm diameter: larger aneurysms have a higher risk of rupture 2, 4, 3.
- Gender: women have a higher risk of rupture than men, especially at smaller aneurysm diameters 5, 6, 3.
- Expansion rate: aneurysms that expand more quickly have a higher risk of rupture 3.
- Body size: women with smaller body sizes are at greater risk of rupture 6.