USPSTF Recommends Screening Older Men Who Smoked for AAA

Other Screening Recommendations Vary Based on Risk Factors

July 08, 2019 11:14 am Chris Crawford – On June 18, the U.S. Preventive Services Task Force posted a draft recommendation statement and draft evidence review on screening for abdominal aortic aneurysm in asymptomatic patients.

For men this age who have never smoked, the USPSTF recommends that physicians selectively offer screening with ultrasonography -- a "C" recommendation. In such instances, patients and physicians should consider the balance of benefits and harms of screening based on evidence relevant to the patient's medical history, family history of AAA, other risk factors and personal values.

As for women, the task force said they are significantly less likely to experience AAA than men and have a higher risk of harm from treatment of aneurysm than do men. Treatment can lead to surgeries that may be unnecessary, harmful and potentially cause death. For these reasons, the USPSTF recommends against routine screening for AAA with ultrasonography in women who have never smoked and have no family history -- a "D" recommendation.

However, for women ages 65-75 who are current or past smokers or who have a family history of AAA, the USPSTF concluded that current evidence is insufficient to assess the balance of benefits and harms of screening for AAA with ultrasonography and recommends physicians use their judgment on who to screen -- an "I" recommendation.

"More research is needed to determine the benefits and harms of screening women who have ever smoked or who have a family history of AAA," said task force member Chyke Doubeni, M.D., M.P.H., in the release. "The evidence shows that women who have never smoked and don't have a family history of AAA do not benefit from screening."

This draft recommendation statement is consistent with the USPSTF's 2014 final recommendation on the topic.

The AAFP supported the task force's recommendation at that time.

Draft Recommendation Highlights

The USPSTF commissioned a systematic evidence review to update its 2014 recommendation on screening for AAA, examining evidence on the effectiveness of one-time and repeated screening for AAA, the associated harms of screening, and the benefits and harms of available treatments for small aneurysms (3-5 cm in diameter) identified through screening.

Four large, population-based randomized controlled trials that predominantly enrolled men 65 or older examined the effectiveness of one-time screening for AAA. They are the

• Multicentre Aneurysm Screening Study (good quality);
• Viborg County, Denmark, screening trial (good quality);
  
• Chichester, U.K., screening trial (fair quality); and
  
• Western Australia screening trial (fair quality).

Reported mean (or median) ages ranged from 67.7 to 72.6 years; the oldest participants were 83.

The prevalence of AAA in male participants ranged from 4% to 7.6% across the studies. Most screen-detected aneurysms were small (less than or equal to 4-4.5 cm in diameter); 0.3% to 0.6% of screened participants had an aneurysm measuring 5 cm or larger or 5.5 cm or larger in diameter.

The Chichester trial was the only study reviewed that included women (ages 65-80). It found a low prevalence of AAA in women (1.3%), and 75% of screen-detected AAAs in women were 3-3.9 cm in diameter. More than two-thirds of deaths from AAA occurred in women 80 or older.

Pooled analysis of AAA-related mortality from the four trials showed a statistically significant 35% reduction associated with invitation to screening. The number needed to screen was 305 men to prevent one AAA death. Invitation to screening was also associated with a statistically significant reduced rate of rupture; number needed to screen was 246 men to prevent one AAA rupture.

The pooled results also showed a reduction in emergency surgery in the invitation-to-screening group. Screening 1,000 men for AAA would decrease the number of emergency procedures by two.

As for comparative treatment modalities, four trials evaluated early surgical intervention compared with surveillance of smaller aneurysms (4 cm to 5.4 cm in diameter). Two good-quality open-repair trials and two fair-quality endovascular aneurysm repair trials showed no differences in all-cause and AAA-related mortality.

A reduction in rupture rate was seen, however, with early open surgery compared with surveillance for small AAAs in the Aneurysm Detection and Management Veterans Affairs trial and the U.K. Small Aneurysm trial.

Seven RCTs that examined antibiotics, antihypertensive medications (e.g., ACE inhibitors, calcium channel blockers and propranolol), and a mast cell stabilizer showed no significant effect on AAA growth compared with placebo.

Each of the four older screening trials and a more recent population-based screening RCT, the Viborg Vascular trial, showed an increase of about 40% in elective surgeries in the intervention group compared with the control group.

Family Physician's Perspective

AAFP Commission on Health of the Public and Science member Kenneth Fink, M.D., M.G.A., M.P.H., of Honolulu, told AAFP News that this draft recommendation remains essentially unchanged from the USPSTF's previous recommendation.

Regarding the C recommendation for screening men ages 65-75 who have never smoked, Fink said the lower prevalence of AAA in this group "decreases the yield of screening and thereby the potential benefit."

"When balancing potential benefits and harms, the USPSTF concluded that screening is of small net benefit for men age 65-75 years who never smoked," he noted.

As for the vastly different recommendations for men and women, Fink said men are estimated to have four to six times the prevalence of AAA compared with women.

"The differing prevalence of atherosclerosis, a risk factor for AAA, by gender likely contributes to this," he explained.

Up Next

The USPSTF is accepting comments on the draft recommendation statement and draft evidence reviewon screening for AAA until 8 p.m. EDT on July 15. All comments received will be considered as the task force prepares its final recommendation.

The AAFP will review the USPSTF's draft recommendation statement and supporting evidence and will provide comments to the task force. The Academy will release its own recommendation on the topic after the task force finalizes its guidance.