New guideline for screening for abdominal aortic aneurysms

A new screening guideline from the Canadian Task Force on Preventive Health Care (CTFPHC) for abdominal aortic aneurysms (AAAs), which cause approximately 1244 deaths every year in Canada, recommends one-time ultrasonography screening for men aged 65 to 80 years.

The guideline is published in CMAJ (Canadian Medical Association Journal)

An AAA is a swelling, or aneurysm, of the aorta, the main blood vessel that carries blood from the heart to the lower part of the body. In Canada, an estimated 20 000 people are diagnosed with an AAA annually.

An AAA results from a weakening in a section of the aortic wall in the abdomen, which bulges because of pressure from blood flow. The aneurysm may grow and eventually rupture, causing death from hemorrhage.

Risk factors include male sex, smoking, advanced age and a family history of AAA.

"The prevalence of AAA among men aged 65 to 80 is reported to be four to five times higher than in women of the same age," said Dr. Harminder Singh, member of the task force and chair of the guideline working group. "Women are unlikely to benefit from being screened for AAA. The benefit of screening men over 80 years of age is likely to be lower than in younger men, due to their greater risk from interventions to repair an AAA."

The new guideline is based on evidence, including 4 randomized controlled trials, published since the last CTFPHC guideline on AAA that was released in 1991.

Recommendations:

• One-time screening with ultrasonography for AAA for men aged 65 to 80. (Weak recommendation; moderate quality of evidence)
• Not screening men older than 80 years of age for AAA. (Weak recommendation; low quality of evidence)
• Not screening women for AAA. (Strong recommendation; very low quality of evidence)

Other guidelines, such as those from the US Preventive Services Task Force, recommend screening in men aged 65 to 75 years who have ever smoked and selectively among those who have never smoked.

"Screening men aged 65 to 80 years has a sufficiently positive impact on reducing mortality, rupture and emergency procedures, which outweighs the risk of identification and unnecessary elective procedures of AAA that might never have ruptured," conclude the authors.

The Canadian Task Force on Preventive Health Care has been established to develop clinical practice guidelines that support primary care providers in delivering preventive health care. The mandate of CTFPHC is to develop and disseminate clinical practice guidelines for primary and preventive care, based on systematic analysis of scientific evidence.

For the complete report and accompanying clinician and patient knowledge translation tools, please visit: http://www.canadiantaskforce.ca.