Who should be screened for Abdominal Aortic Aneurysm?
Abdominal aortic aneurysm screenings should be routinely recommended only when a positive net benefit (benefits outweigh harms) exists. There is good evidence that screening and surgical repair of large aneurysms (5.5 cm or greater) in men 65-75 years of age.
Consequently, a screening should be routinely recommended only when a positive net benefit (benefits outweigh harms) exists. There is good evidence that screening and surgical repair of large aneurysms (5.5 cm or greater) in men 65-75 years of age who have ever smoked leads to decreased deaths.
As a result, only this group stands to benefit the most from early detection and reparative surgical treatment.
Men aged 65-75 who have never smoked and men age <65 are at lower risk.
Men age >75 are at higher risk for AAAs, but the increased presence and limited life expectancy decreases.
Women are at lower risk for AAAs. Thus, the net benefit from screening is small and routine screening is not recommended.
What should I know about AAA?
|AAA Size (cm)||Prevalence|
Source: Lederle et al. The Aneurysm Detection and Management Study Screening Program. Validation Cohort and Final Results. Arch Intern Med 2000; 160:1425-1430.
Consequently, the main risk of an aneurysm is the rupture. Most (75-90%) individuals with ruptured AAAs do not survive to hospital discharge. The risk of rupture is proportional to aneurysm size. Larger aneurysms are more likely to rupture than smaller aneurysms. Studies have documented benefit from surgical repair of aneurysms 5.5 cm and larger.
What are the benefits and harms of screening for an Abdominal aortic aneurysm?
Because randomized controlled trials evaluated the benefit of screening found an AAA-related mortality rate of 0.33% in an unscreened population versus 0.19% in a screened population. Screening for AAA does not reduce all-cause mortality. Harms from screening include the morbidity and mortality from surgical repair for those with aneurysms needing treatment. Among men aged 65-75 who have ever smoked, the number needed to screen to prevent one AAA-related death within the next 5 years is 500.
Especially Relevant is the following Web site for tools and resources to help you assist your patients with quitting: http://www.publichealth.va.gov/smoking/publications.asp. You can also refer patients to the national quitline at 1-800-QUIT-NOW (1-800-784-8669).
What should I do with AAA screening test results?
Normal screening exam (<3.0 cm)
Yet if the exam is normal (i.e., maximal aortic diameter <3 cm), further screenings are not mandatory.
Small to a medium-sized aneurysm detected (3.0-5.4 cm)
Because these aneurysms will need surveillance since they are at risk of becoming larger. The typical expansion rate is ~ 0.3-0.4 cm per year, on average. Larger aneurysms expand faster than smaller ones so surveillance intervals depend on size.
|AAA Size||Surveillance interval|
|3.0-3.9 cm||2-3 years|
|4.0-5.4 cm||6 months|
Source: Lederle et al. Ultrasonographic Screening for Abdominal Aortic Aneurysms. Ann Intern Med 2003 1396:516-22.
As a result of a change during the surveillance period, continued AAA surveillance should occur only if the patient remains a good surgical candidate and has a reasonable life expectancy.
A large aneurysm detected (≥5.5 cm)
Consequently, surgical mortality from elective, open AAA repair is 4-5% and about one-third of major complications including cardiac, pulmonary, and GU (impotence) problems.