Lower threshold for abdominal aortic aneurysm repair linked to reduced mortality

1. Repair of intact abdominal aortic aneurysms (AAA) was performed at significantly lower mean diameters in the United States than England from 2005 through 2012, with the rate of endovascular repair significantly higher in the United States.

2. During this period, the rate of hospitalization due to a ruptured aneurysm and aneurysm-related death was significantly higher in England than the United States.

Evidence Rating Level: 2 (Good)       

Study Rundown: AAA is a common and potentially life-threatening condition. Rupture is an often fatal surgical emergency and most effectively prevented with elective repair. Current international practice guidelines indicate the risk of rupture outweighs surgical risks when an aneurysm diameter exceeds 55 mm in men or 50 mm in women. However, this is a debated threshold and there is marked clinical deviation from this standard. This study examined the differences between the threshold of repair and aneurysm-related mortality in England and the United States. The results demonstrated that the mean diameter at the time of repair was significantly higher in England while the overall frequency of repair was significantly less common (especially endovascular). Furthermore, England demonstrated a significantly higher rate of hospitalization due to aneurysm rupture and aneurysm-related death.

Screening data at the study onset indicated that prevalence data of aneurysms was similar between both counties. Though the clinically recognized databases were used, the study was limited by available governmental data in each country. Of note, autopsy rates are low in both the United States and England and confirmation of aneurysm-related mortality is therefore difficult. Surgical complications may also have been underreported as a result of the government databases used.

Click to read the study, published today in NEJM

Relevant Reading: A randomized trial comparing conventional and endovascular repair of abdominal aortic aneurysms

In-Depth [retrospective cohort]: This retrospective cohort study assessed the threshold for repair of intact abdominal aneurysms and any differences in aneurysm-related morbidity and mortality between England and the United States. Cases of endovascular or open repair of intact aneurysms and cases of hospitalizations from ruptured aneurysms were identified from 2005 to 2012. This was compared with data on long-term survival, aneurysm-related deaths, and maximum aneurysm diameter before surgery from government databases of each country. All data was standardized for population age and sex.

From 2005 to 2012, repair of intact aneurysms was less common per 100 000 individuals in England than the United States (OR 0.49; 95% CI, 0.48 to 0.49; p < 0.001). Endovascular procedures were significantly lower in England (45.5% v. 67.0%, p < 0.001). No differences between in-hospital mortality in patients undergoing surgery were found (OR 1.04; 95% CI, 0.96 to 1.12; p = 0.40). Hospitalization from aneurysm rupture was significantly more frequent in England than the United States (OR 2.23; 95% CI, 2.19 to 2.27; p < 0.001), as was aneurysm-related death (OR 3.60; 95% CI, 3.55 to 3.64; p < 0.001). The difference in aneurysm-related death remained significant after adjusting for smoking, hypertension, and hypercholesterolemia. Intact aneurysms at the time of repair were a mean 5.3±0.3 mm larger in England compared to the time of repair in the United States (p < 0.001).

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