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Prognosis of abdominal aortic aneurysms: a population-based study
1Department of Radiology, University Hospital, Boston University School of Medicine, MA 02118.
Investigative Radiology
|June 1, 1991
Summary
This study on abdominal aortic aneurysms found a slower expansion rate than previously thought. Small aneurysms (<5.0 cm) have a significantly lower rupture risk, challenging prior beliefs.
Area of Science:
- Vascular Surgery
- Epidemiology
- Medical Imaging
Background:
- Abdominal aortic aneurysms (AAAs) are a significant vascular disease.
- Understanding AAA natural history and rupture risk is crucial for patient management.
- Previous estimates suggested a faster expansion rate and higher rupture risk for smaller AAAs.
Purpose of the Study:
- To determine the natural history of abdominal aortic aneurysms.
- To assess the rate of AAA expansion.
- To evaluate the risk of AAA rupture based on initial size.
Main Methods:
- Retrospective review of AAA cases in Rochester, Minnesota (1951-1984).
- Inclusion of 370 patients with detailed ultrasound data.
- Exclusion of patients with rapid aneurysm changes within 48 hours of initial ultrasound.
Main Results:
- Median AAA expansion rate was 0.21 cm/year; mean was 0.26 cm/year.
- No ruptures observed in aneurysms <5.0 cm diameter during the study.
- Eight-year rupture incidence was 0% for aneurysms <3.5 cm and 5% for those 3.5-4.9 cm.
- 25% of aneurysms >5.0 cm at baseline ruptured by eight years.
Conclusions:
- The natural history of AAAs suggests a slower expansion rate than the commonly accepted 0.4 cm/year.
- AAAs <5.0 cm diameter possess a substantially lower rupture risk than previously estimated.
- Geographically defined population data provide a more accurate reflection of AAA natural history.