Screening Results from a Large United Kingdom Abdominal Aortic Aneurysm Screening Center in the Context of Optimizing United Kingdom National Abdominal Aortic Aneurysm Screening Programme Protocols

Background: After its introduction in six pilot centers in 2009, the National Abdominal Aortic Aneurysm Screening Programme (NAAASP) is now established across the United Kingdom, demonstrating significant benefit in terms of fewer emergency surgeries and reduced 30-day surgical mortality. However, according to publication of data on annual screened abdominal aortic aneurysm (AAA) detection, a lower incidence than predicted in the original screening trials has been found. In this audit we assessed features and risk factors of men found to have a positive scan result in the southwest London AAA screening program, to determine screening yield for subgroups of populations and assess the case for a more targeted screening program.

Methods: Data from the NAAASP screening database for England were extracted for all men who attended screening from the April 1, 2009 through October 16, 2013 in the southwest London area. Primary outcomes were aneurysm prevalence, risk factors, and incidence within subgroups. Results were reviewed against nationally reported data and London census data.

Results: Of 24,891 men who were screened in the southwest London program during this period, 292 AAAs were identified (1.18%). Patients were asked to categorize their ethnic background according to classifications provided by the office of national statistics. Those at highest risk of AAA were white-British (1.35%), followed by black and black British (0.65%), and Asian/Asian British (0.23%). Number needed to screen to identify one AAA was calculated as 78, 154, and 431, respectively. The relative proportions of patients screened were similar to that described in the most recent United Kingdom census, except for white-British patients, indicating a shortfall in acceptance of screening invitations in this group. There were no AAA identified in Chinese men. A positive smoking history was found in 90%, a confirmed diagnosis of hypertension in 50%, hypercholesterolemia in 34%, and ischemic heart disease in 21%.

Conclusions: Within southwest London, AAA was most strongly associated with being white-British, a previous or current smoker, and known hypertension. Targeted education in patient groups with identified risk factors for AAA should be considered to improve screening yield without excluding any subgroup from the screening program. This could draw on resources released by unused scans because of lower than predicted prevalence. AAA diagnosis should be seen as an opportunity to address the increased all-cause mortality associated with aortic aneurysmal disease.