Thresholds for Abdominal Aortic Aneurysm Repair in England and the United States

Abstract

Background: Thresholds for repair of abdominal aortic aneurysms vary considerably among countries.

Methods: We examined differences between England and the United States in the frequency of aneurysm repair, the mean aneurysm diameter at the time of the procedure, and rates of aneurysm rupture and aneurysm-related death. Data on the frequency of repair of intact (nonruptured) abdominal aortic aneurysms, in-hospital mortality among patients who had undergone aneurysm repair, and rates of aneurysm rupture during the period from 2005 through 2012 were extracted from the Hospital Episode Statistics database in England and the U.S. Nationwide Inpatient Sample. Data on the aneurysm diameter at the time of repair were extracted from the U.K. National Vascular Registry (2014 data) and from the U.S. National Surgical Quality Improvement Program (2013 data). Aneurysm-related mortality during the period from 2005 through 2012 was determined from data obtained from the Centers for Disease Control and Prevention and the U.K. Office of National Statistics. Data were adjusted with the use of direct standardization or conditional logistic regression for differences between England and the United States with respect to population age and sex.

Results: During the period from 2005 through 2012, a total of 29,300 patients in England and 278,921 patients in the United States underwent repair of intact abdominal aortic aneurysms. Aneurysm repair was less common in England than in the United States (odds ratio, 0.49; 95% confidence interval [CI], 0.48 to 0.49; P<0.001), and aneurysm-related death was more common in England than in the United States (odds ratio, 3.60; 95% CI, 3.55 to 3.64; P<0.001). Hospitalization due to an aneurysm rupture occurred more frequently in England than in the United States (odds ratio, 2.23; 95% CI, 2.19 to 2.27; P<0.001), and the mean aneurysm diameter at the time of repair was larger in England (63.7 mm vs. 58.3 mm, P<0.001).

Conclusions: We found a lower rate of repair of abdominal aortic aneurysms and a larger mean aneurysm diameter at the time of repair in England than in the United States and lower rates of aneurysm rupture and aneurysm-related death in the United States than in England. (Funded by the Circulation Foundation and others.).

Figure 1. Repair of Intact Abdominal Aortic Aneurysms in England and the United States, 2005–2012

Shown are the incidence of repair of intact abdominal aortic aneurysms (Panel A) and the percentage of all repairs of intact abdominal aortic aneurysms that were endovascular procedures (Panel B). Data on patients in England are from the Hospital Episode Statistics database, and data on patients in the United States are from the Nationwide Inpatient Sample.

Figure 2. Kaplan–Meier Estimates of 3-Year Survival after Repair of Intact Abdominal Aortic Aneurysms in England and the United States, 2005–2008

Shown are survival curves after all repairs (Panel A), after endovascular repair (Panel B), and after open surgical repair (Panel C) of intact abdominal aortic aneurysms. Data on patients in England are from the Hospital Episode Statistics database, and data on patients in the United States are from Medicare.

Figure 3. Incidence of Hospitalization and Death due to Abdominal Aortic Aneurysms in England and the United States, 2005–2012

Panel A shows the incidence of hospitalization for ruptured abdominal aortic aneurysms. Data on patients in England are from the Hospital Episode Statistics database, and data on patients in the United States are from the Nationwide Inpatient Sample. Panel B shows the number of deaths related to abdominal aortic aneurysms. Data on patients in England are from the Office of National Statistics, and data on patients in the United States are from the Centers for Disease Control and Prevention.

Figure 4. Diameter of Abdominal Aortic Aneurysms at the Time of Repair in England in 2014 and in the United States in 2013

Shown are probability density function curves of the diameter of abdominal aortic aneurysms at the time of repair in men (Panel A) and women (Panel B). Data on patients in England are from the U.K. National Vascular Registry, and data on patients in the United States are from the U.S. National Surgical Quality Improvement Program (NSQIP).

Figure 5. Diameter of Abdominal Aortic Aneurysms and Number of Repairs in England and the United States

Panel A shows a frequency histogram and probability density function distribution for the diameter of abdominal aortic aneurysms among the first 700,000 men screened in England. This screening occurred between April 2009 and August 2014. A total of 48 men per 100,000 men screened had aneurysms at or above the mean diameter for aneurysm repair in England, as compared with 76 men per 100,000 screened who had aneurysms at or above the mean diameter for aneurysm repair in the United States. Panel B shows the standardized numbers of repairs of abdominal aortic aneurysms in the United States as compared with the expected numbers of repairs of abdominal aortic aneurysms in England. The results are shown after application of the U.S. probability density for repair at various aortic diameters to the prevalence data for abdominal aortic aneurysms in England at each diameter in the U.K. national screening program. Data on patients in England are from the National Health Service Abdominal Aortic Aneurysm Screening Programme, and data on patients in the United States are from the NSQIP.