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Level II – Abdominal Aortic Aneurysm Screening

Level II Services: Preventive services for which clinicians and care systems should assess the need. These services should be recommended to each patient as they have value, but less than those in Level I.

The USPSTF recommendations are fully endorsed by the ICSI Preventive Services work group.
Grade of Recommendation and Level of Certainty as Evaluated by USPSTF
  1. “One-time screening for abdominal aortic aneurysm (AAA) by ultrasonography in men ages 65 to 75 years who have ever smoked.”
  2. “Clinicians selectively offer screening for AAA in men ages 65 to 75 years who have never smoked rather than routinely screening all men in this group.”
  3. “The current evidence is insufficient to assess the balance of benefits and harms of screening for AAA in women ages 65 to 75 years who have ever smoked.”
  4. “Against routine screening for AAA in women who have never smoked.”
(USPSTF Last Revised 2014)
Grade of Recommendation:
  1. B
  2. C
  3. I Statement
  4. D

Level of Certainty:

  1. Moderate
  2. Moderate
  3. Insufficient
  4. Moderate
“Benefits:
Men Ages 65 to 75 Years Who Have Ever Smoked
Four large, population-based, randomized, controlled trials (RCTs) show that invitation to one-time screening for AAA is associated with reduced AAA-specific mortality in men. This benefit begins three years after testing and persists up to 15 years. In addition, risk reduction for AAA rupture and emergency surgery persists up to 10 to 13 years.
In the two highest-quality trials, the relative reduction in AAA-specific mortality after 13 years was 42 to 66%. In the largest trial, where prevalence of AAA was approximately 5% in the screened group, screening was associated with an absolute risk reduction in AAA death of 1.4 per 1,000 men.
Abdominal aortic aneurysms are most prevalent in men who have ever smoked, occurring in approximately 6 to 7% of this population. This prevalence increases the importance of screening in these men because it maximizes the absolute benefit that could be achieved (that is, it improves the likelihood that men in this group will benefit from screening). Convincing evidence shows that one-time screening for AAA with ultrasonography results in a moderate benefit in men ages 65 to 75 years who have ever smoked.
Men Ages 65 to 75 Years Who Have Never Smoked
Screening men overall reduces AAA-specific death, rupture and emergency surgery. However, the lower prevalence of AAA in men who have never smoked (approximately 2%) substantially reduces the absolute benefit (that is, it greatly lowers the probability that men in this group will benefit from screening). Adequate evidence shows that one-time screening for AAA with ultrasonography results in a small benefit in men ages 65 to 75 years who have never smoked.
Women Ages 65 to 75 Years Who Have Ever Smoked
Only one RCT on screening for AAA included women. It detected no difference in the rate of AAA rupture, AAA-specific mortality or all-cause mortality between women invited for screening and the control group. However, the trial was ultimately underpowered to detect differences in health outcomes by sex; as such, the results do not rule out the possibility of a small benefit of screening in this population.
Women age 70 years who have ever smoked have a relatively low prevalence of AAA (approximately 0.8% overall and about 2% for current smokers). Evidence is inadequate to conclude whether one-time screening for AAA with ultrasonography is beneficial in women ages 65 to 75 years who have ever smoked.
Women Who Have Never Smoked
The prevalence of AAA in women who have never smoked is low (0.03 to 0.60% in women ages 50 to 79 years). The evidence also shows no apparent benefit of screening for AAA in women. The USPSTF therefore concludes that adequate evidence shows that the absolute benefit of one-time screening for AAA with ultrasonography in women who have never smoked can effectively be bounded at none or almost none.
Harms:
In the available trials, groups invited to screening were approximately twice as likely as control groups to have any AAA surgery within three to five years, predominantly driven by an increase in elective surgeries. More than 90% of AAAs identified by screening was below the 5.5-cm threshold for immediate repair. Detecting smaller AAAs generally leads to long-term (potentially lifelong) surveillance.
A person's risk for death related to elective surgery for AAA is lower than that for death related to emergency surgery for AAA rupture. However, the increase in the overall rates of detection and surgery in the screening groups still potentially represents a harm. A proportion of AAAs will never rupture because they do not advance to conditions for the rupture to appear or because a person dies of a competing cause.
The exact extent of over-diagnosis and overtreatment is difficult to estimate. One study from Massachusetts General Hospital reviewed 24,000 consecutive autopsies between 1952 and 1975 and found that 75% of the 473 patients who died with an undetected or unoperated AAA had a cause of death not related to the AAA (41% of AAAs were >5.1 cm in diameter). Given that even elective treatment of AAA is associated with some risk for perioperative mortality, overtreatment is an important issue to consider when deciding whether to screen for this condition.
One study reported that women had a higher risk for death related to AAA surgery than men; death rates of women and men were approximately 7% versus 5% for open repair and 2% versus 1% for endovascular repair, respectively. Evidence is limited and conflicting about the effect of screening for AAA on quality of life or psychological status (for example, anxiety). Convincing evidence shows that the harms associated with one-time screening for AAA with ultrasonography are at least small in all populations and potentially higher in women because of their higher risk for operative mortality.
Benefits-Harms Assessment:
The USPSTF concludes with high certainty that screening for AAA with ultrasonography in men ages 65 to 75 years who have ever smoked has a moderate net benefit.
The USPSTF concludes with moderate certainty that screening for AAA with ultrasonography in men ages 65 to 75 years who have never smoked has a small net benefit.
The USPSTF concludes that the evidence is insufficient to determine the balance of benefits and harms of screening for AAA in women ages 65 to 75 years who have ever smoked.
The USPSTF concludes with moderate certainty that the harms of screening for AAA outweigh any potential benefits in women who have never smoked.”
Relevant Resources:
http://www.uspreventiveservicestaskforce.org/uspstf/uspsaneu.htm
Implementation Tools and Strategies:
Screening for Abdominal Aortic Aneurysm