Objective: To assess the benefits and harms of AAA screening programs and approaches to treating small aneurysms, and to determine screening yield for subgroup populations.
Data Sources: We performed a search of MEDLINE, the Database of Abstracts of Reviews of Effects, and the Cochrane Collaboration Registry of Controlled Trials for studies published from January 2004 through June 1, 2012. We supplemented searches by examining bibliographies from retrieved articles, previous U.S. Preventive Services Task Force reviews, and consulting outside experts. We searched federal agency trial registries for ongoing and/or unpublished trials.
Study Selection: Two reviewers independently reviewed citations against a priori inclusion and exclusion criteria. Potentially relevant articles were then independently evaluated by two reviewers against the same inclusion criteria and quality-rated using U.S. Preventive Services Task Force criteria. Resolution of discrepancies occurred through discussion with a third reviewer. A single investigator extracted study characteristics and results into tables and a second reviewer checked accuracy.
Data Analysis: Evidence for all key questions (KQs) was qualitatively synthesized. Quantitative synthesis of outcomes for KQs 1, 3, 4, and 5 used a random-effects model as the primary analysis, with sensitivity analyses using a fixed-effects model. For KQ 1 only, additional sensitivity analyses were conducted using Peto odds ratios and hazard ratios, where reported.
Results: Based on four fair- to good-quality, population-based, randomized, controlled trials (RCTs) (N=137,214), one-time invitation for AAA screening in men age 65 years and older reduced AAA rupture and AAA-related mortality for up to 10 years, but had no effect on all-cause mortality after up to 15 years. Based on one fair-quality population-based RCT in women (N=9,342), screening had no AAA-related or all-cause mortality benefit. We found insufficient direct evidence to make conclusions about the yield of various high-risk screening approaches. We identified a group of heterogeneous, mostly small cohort studies examining rescreening yield that provided no clear data on which to base conclusions. Few studies addressed differences in rescreening yield by population subgroup or screening interval. Based on four fair-quality RCTs (N=137,214), invitation for screening was associated with some harms (i.e., more overall surgeries and more elective surgeries) but fewer emergency operations and decreased 30-day operative mortality at up to 10 to 15 years of followup. Four observational studies (N=1150) suggested no long-term quality of life difference from screening, although one study showed lower Short-form 36-item Health Survey scores at 6 weeks in the screened group, which did not persist.
Analysis of two good-quality RCTs (N=2,226) demonstrated that early open surgery compared with surveillance for small AAA (4 to 5 cm) decreased AAA rupture with attenuated benefit after 5 years, but did not alter AAA-related or all-cause mortality after up to 12 years of followup. One RCT showed no subgroup differences in all-cause mortality or AAA-related mortality by age, sex, or AAA diameter for open surgery versus surveillance. Open surgery compared with surveillance resulted in similar 30-day postoperative mortality and quality of life but fewer postoperative complications, particularly perioperative myocardial infarction. Meta-analysis of two underpowered fair-quality RCTs (N=1,088) of early EVAR compared with surveillance in small AAA found that EVAR does not reduce all-cause mortality, AAA-related mortality, or AAA rupture. EVAR complications reported in two RCTs and two registry studies (N=2,440) included systemic complications (15%), endoleaks (10%), and reintervention (4%) but no difference in operative mortality. One fair-quality RCT (N=339) suggested higher quality of life in early EVAR compared with surveillance in the first 6 months that did not persist at 3-year followup. A few fair-quality, small heterogeneous RCTs examined pharmacotherapy compared with surveillance for small AAA, with inconsistent results in altering AAA growth rates. There were few adverse reactions reported for antibiotics in these small trials but propranolol was poorly tolerated, leading to a high withdrawal rate.
Limitations: The four large population-based screening trials, while robust in numbers, almost exclusively represent a population of older Caucasian men from nonU.S. populations. Other than for age and sex, there is no direct evidence on AAA screening benefit for other subgroups by race, family history, smoking history, or cardiovascular risk. There is limited information on rescreening yield overall and by subgroup derived from one Department of Veterans Affairs trial. Two RCTs examining EVAR versus surveillance for small AAA were prematurely stopped due to futility analysis demonstrating less than 1 percent chance of finding a difference in AAA rupture or AAA-related mortality. These studies could be underpowered to detect other differences in health outcomes. The four RCTs addressing pharmacotherapy versus surveillance for AAA were small and studied heterogeneous populations. Quality of life studies examining possible harms from screening and treatment are small and examine outcomes at different time points in different populations.
Conclusions: One-time invitation for AAA screening in men ages 65 years and older was associated with decreased AAA rupture and AAA-related mortality but no difference in all-cause mortality. Treatment of small, screen-detected AAA with early open or EVAR surgery did not result in improved health outcomes compared with surveillance. Short-term but not long-term differences in quality of life have been seen with screening for AAA in those who screen positive.