The following are key points to remember about thresholds for abdominal aortic aneurysm repair in England and the United States:

1. The decision about whether to repair an abdominal aortic aneurysm requires consideration of a balance of risks, including aneurysm rupture if surgery is not performed and death due to aneurysm repair itself, as well as consideration of an individual patient’s probable life expectancy.
2. The aneurysm diameter is the best predictor of aneurysm rupture; the risk increases exponentially with an increasing diameter. Therefore, the aneurysm diameter is a key determinant of the threshold for intervention.
3. International guidelines recommend that intervention should be considered once the aneurysm diameter exceeds 55 mm in men or 50 mm in women.
4. However, the considerable variation in clinical practice reflects uncertainty regarding the best threshold for intervention.
5. Among patients with intact (nonruptured) abdominal aortic aneurysms, the rate of repair over an 8-year period was half as high in England as in the United States.
6. There was also a difference between the two countries in the mean aneurysm diameter at the time of repair, with an adjusted difference of 5.3 mm.
7. National screening data for England suggest that these two observations may be related, because the prevalence of aneurysms at the mean diameter for repair in the United States was almost twice as high as the prevalence of aneurysms at the mean diameter for repair in England.
8. Endovascular repair was used less frequently in England than in the United States, and endovascular repairs were performed at lower aneurysm diameters (in both countries) than open repair.
9. Among patients who were selected for aneurysm repair, in-hospital mortality and the rates of 3-year survival were similar in England and the United States. This finding suggests that the increased rate of aneurysm repair in the United States did not come at the expense of greater perioperative or postoperative risk.
10. Two observations from these data suggest that the lower rate of aneurysm repair in England may have adverse consequences. Although the rate of hospitalization due to aneurysm rupture decreased in both countries over the 8 years studied, this rate was more than twice as high in England as in the United States. In addition, although aneurysm-related mortality also decreased over time in both countries, this rate was 3.5 times as high in England as in the United States.

Keywords: Aneurysm, Ruptured, Aortic Aneurysm, Abdominal, Aortic Rupture, Endovascular Procedures, Hospital Mortality, Life Expectancy, Prevalence, Primary Prevention, Risk, Uncertainty, Vascular Diseases

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