Abdominal Aortic Aneurysm - Screening

Screening

A clinical practice guideline by the U.S. Preventive Services Task Force "recommends one-time screening for abdominal aortic aneurysm (AAA) by ultrasonography in men age 65 to 75 years who have ever smoked". This is a grade B recommendation. A re-analysis of the meta-analysis estimated a number needed to screen of approximately 850 patients.

The largest of the randomized controlled trials on which this guideline was based studied a screening program that consisted of:

Screening men ages 65–74 years (not restricted to ever smokers). 'Men in whom abdominal aortic aneurysms (> or =3 cm in diameter) were detected were followed-up... Patients with an aortic diameter of 3·0–4·4 cm were rescanned at yearly intervals, whereas those with an aortic diameter of 4·5–5·4 cm were rescanned at 3-monthly intervals ... Surgery was considered on specific criteria (diameter > or =5.5 cm, expansion > or =1 cm per year, symptoms)'.

This trial reported significant short (number needed to screen after 4 years of approximately 590 to prevent nonfatal ruptured AAA plus AAA-related deaths) and long term (number needed to screen after 7 years of approximately 280 to prevent nonfatal ruptured AAA plus AAA-related deaths) benefit and cost effectiveness. Subsequent randomized controlled trials also found benefit:

• number needed to screen after 4 years of 300
• number needed to screen after and after 7 years of 563 (calculation).

In the U.S., effective January 1, 2007, provisions of the SAAAVE Act (Screening Abdominal Aortic Aneurysm Very Efficiently) now provide a free, one-time, ultrasound AAA screening benefit for those qualified seniors. Men who have smoked at least 100 cigarettes during their life, and men and women with a family history of AAA qualify for the one-time ultrasound screening. Enrollees must visit their healthcare professional for their Welcome to Medicare physical within six months of enrollment to qualify for the free screening. The Welcome to Medicare Physical Exam must be completed within the first six months of Medicare eligibility, but there is no published time limit thereafter for completion of the AAA screening. Providers who perform the physical and order the AAA screening need to document the AAA risk factors.

In the U.K., by March 2013 screening is expected to be offered to all men in England in their 65th year. Analysis of the 10-year Multicentre Aneurysm Screening Study (MASS) data shows that the NHS AAA Screening Programme will prevent significant numbers of AAA ruptures and AAA deaths.

The study also proves that the number of lives saved will outweigh the number It also proves that the number of lives saved will greatly outweigh the number of post-elective surgery deaths.

The following figures use the 10-year MASS data and assume an 80% attendance for screening and a 5% post-elective surgery mortality:

• 240 men need to be invited (192 scanned) to save one AAA death over 10 years

• Each 2,080 men invited for screening (1,660 scanned) result in one extra post-elective surgery death

This means that over 10 years, for every 10,000 men scanned under the NAAASP (National Abdominal Aortic Aneurysm Screening Programme), 65 AAA ruptures will be prevented, saving 52 lives. However, there will also be six post-elective surgery deaths involving men whose aneurysm is detected under the screening programme.