Objective:

To systematically review evidence about the benefits and harms of ultrasound-based abdominal aortic aneurysm (AAA) screening and small aneurysm treatment in primary care populations, including subpopulations of older adults, women, smokers, racial/ethnic subgroups, and those with a family history of AAA.

Data Sources:

We performed a search of MEDLINE, PubMed (Publisher Supplied only), the Database of Abstracts of Reviews of Effects, and the Cochrane Collaboration Registry of Controlled Trials for relevant English-language studies published between January 2012 and September 14, 2018. Additionally, we re-evaluated all studies included in the 2014 USPSTF review. We supplemented searches by examining bibliographies from retrieved articles and consulting outside experts. We searched Federal Agency trial registries for ongoing and/or unpublished trials.

Study Selection:

Two investigators independently reviewed identified abstracts and full-text articles against a set of a priori inclusion and quality criteria. Resolution of disagreements occurred through discussion with a third reviewer. We included the following study designs: randomized, controlled trials (RCTs) for the effectiveness of screening and small aneurysm treatment interventions; RCTs and large cohort studies for rescreening effectiveness and screening/rescreening harms; and RCTs, large cohort studies, and vascular survey registries for small aneurysm treatment harms.

Data Analysis:

One investigator abstracted data into evidence tables and a second investigator checked accuracy. We qualitatively synthesized the data for each Key Question and performed meta-analyis on trial results for Key Questions 1 and 3. Our analyses utilized the Peto method to pool odds ratios (ORs) (for AAA-related mortality, rupture, and operations) and the DerSimonian and Laird random-effects model to pool calculated risk ratios (for all-cause mortality). Subgroup-specific results were abstracted and qualitatively synthesized from any included studies reporting outcomes for our a priori list of subgroups.

Results:

Based on four fair- to good-quality, population-based RCTs (N=124,929), the invitation for screening men age 65 years or older was associated with a 35 percent reduction in AAA-related mortality and a 38 percent reduction in AAA rupture rate; screening was also associated with a 43 percent reduction in the number of emergency surgeries. There was no statistically significant difference, however, in all-cause mortality at 12- to 15-year followup. Based on eight heterogeneous, short-term rescreening studies (N=8,018) with a variety of protocols (rescreening annually to 5 years, with a total of one to six repeated scans), AAA-related mortality up to 5 to 12 years appears to be rare (<3%) among persons with normal aortas (<3 cm) on the initial scan. Upon rescreening, few aortas (0% to 2.2%) expanded to larger than 5 cm at 5 years and 0 to 15 percent had progressed at 10 years. One-time screening is associated with a nearly 44 percent more surgeries in the invited group compared to the control group (K=5; N=175,085; Peto OR, 1.44 [95% CI, 1.34 to 1.55]), largely driven by elective operations (Peto OR, 1.75 [95% CI, 1.61 to 1.90]). There was no statistically significant difference in 30-day mortality rates in the invited vs. control groups for either elective surgeries or emergency surgeries at the 12- to 15-year followup. Five studies generally showed no significant long-term differences in quality of life, anxiety, and depression scores between persons who screen positive and those who screen negative up to 12 months. Four fair- to good-quality studies (N=3,314) of small aneurysm (4.0 to 5.4 cm) treatment demonstrate that endovascular repair (EVAR) and open repair are associated with no difference in AAA-related mortality or all-cause mortality compared to surveillance. Early open repair, however, was found to significantly reduce the rate of rupture compared to surveillance. These four trials show an approximately 50 to 100 percent increase in procedures in the early surgery group and no difference in 30-day mortality rates. Complications such as cardiac, pulmonary, and renal events reported in registry databases were generally comparable to those reported in the trials, with the exception of reintervention rates for open repair, which were higher in the registries than in the open trial reporting this outcome. Seven fair-quality, short-term drug trials (N=1,553) of antibiotics, antihypertensive medications, and mast cell stabilizers showed no overall effect on AAA growth compared to placebo. Propranolol trials, however, reported high withdrawals due to adverse events, but other drugs appear to be well tolerated.

There are limited data on screening effectiveness or harms in subpopulations; outcomes were rarely reported by subpopulation and when available, the data are full of methodologic limitations. For small aneurysm treatment, available evidence from registry data (k=3; N=14,424) shows that women have higher surgical complications and postoperative mortality compared to men. Two trials reported no differences in all-cause mortality associated with open surgical repair of small aneurysm by age, sex, or smoking history.

Limitations:

Trials included mostly white men outside of the United States. Information for subgroups and about rescreening was limited.

Conclusions:

A one-time invitation for AAA screening in men age 65 years or older was associated with decreased AAA-related mortality and rupture rates but had little or no effect on all-cause mortality. Screening is associated with higher rates of elective surgery, but there are no long-term differences in the quality of life in persons who screen positive. Treatment of small, screen-detected AAA with early open or EVAR surgery did not result in improved health outcomes compared to surveillance but result in more elective surgeries. There are limited data on pharmacotherapy treatment of small aneurysms showing no statistically significant effect on AAA growth rates. There are limited data on screening effectiveness or harms in subpopulations; small aneurysm surgical complication rates appear to be greater in women than in men.