At what age should screening for Abdominal Aortic Aneurysm (AAA) start?

Screening for Abdominal Aortic Aneurysm (AAA)

AAA screening should begin at age 65 for men who have ever smoked, with a one-time ultrasound examination. 1

Screening Recommendations by Population Group

Men

• Men ages 65-75 who have ever smoked: One-time screening with ultrasonography is strongly recommended (Grade B recommendation) 1
• Men ages 65-75 who have never smoked: Screening may be considered but is not strongly recommended (Grade C recommendation) 1
• Men age ≥75 years: May be considered for screening regardless of smoking history 1

Women

• Women ages 65-75 who have ever smoked: Evidence is insufficient to recommend for or against screening 1
• Women who have never smoked: Routine screening is not recommended 1
• Women age ≥75 years who are current smokers and/or hypertensive: Screening may be considered 1

Family History Considerations

• First-degree relatives of patients with AAA: Screening is recommended starting at age 50, unless an acquired cause can be clearly identified 1

Opportunistic Screening

• Consider opportunistic screening during transthoracic echocardiography in men ≥65 years and women ≥75 years 1

Rationale for Screening

AAA is a potentially fatal condition that often remains asymptomatic until rupture. A ruptured AAA has a mortality rate of over 50%, with median survival of only 9 months for untreated large aneurysms (>7.0 cm) 2. Early detection through screening allows for:

1. Appropriate surveillance of small aneurysms
2. Timely intervention for aneurysms reaching critical size (≥5.5 cm)
3. Risk factor modification to slow aneurysm growth

Screening Method

• Modality: Abdominal ultrasonography is the preferred screening method due to its:
  • High sensitivity and specificity
  • Safety profile
  • Relatively lower cost compared to other imaging modalities 3
  • No radiation exposure

Follow-up After Screening

For patients with detected AAA, follow-up depends on aneurysm size:

• 3.0-3.9 cm: Ultrasound every 2-3 years
• 4.0-4.4 cm: Ultrasound every 12 months
• 4.5-5.4 cm: Ultrasound every 6 months
• ≥5.5 cm: Consider surgical intervention 2

Important Considerations and Caveats

• The prevalence of AAA has been declining in recent years, likely due to decreased smoking rates and better management of cardiovascular risk factors 4
• A single screening at age 65 appears to provide protection for at least 10 years in men with normal aortic diameter at initial screening 5
• Almost 40% of AAAs in 70-year-old men may already be known from other means than screening 4
• Smoking remains the strongest risk factor for AAA development 4

Risk Factor Modification

For patients with detected AAA:

• Complete smoking cessation is crucial
• Blood pressure control (target <130/80 mmHg)
• Statin therapy regardless of cholesterol levels
• Regular moderate exercise 2

By following these evidence-based screening guidelines, clinicians can significantly reduce mortality from ruptured AAA while minimizing unnecessary testing and interventions.