Aetna considers one-time ultrasound screening for abdominal aortic aneurysms (AAA) medically necessary for men 65 years of age or older.

Aetna considers AAA screening experimental and investigational for all other indications because its effectiveness for indications other than the one listed above has not been established.

The U.S. Preventive Services Task Force (USPSTF) recommends one-time screening for abdominal aortic aneurysm (AAA) by ultrasonography in men aged 65 to 75 who have ever smoked.  This recommendation was based on the results of published randomized controlled clinical studies of screening for abdominal aortic aneurysms (Scott et al, 1995; Vardulaki et al, 2002; Scott et al, 2002; Lindholt et al, 2002; Ashton et al, 2002; Norman et al, 2003).

The USPSTF found good evidence that screening for AAA and surgical repair of large AAAs (5.5 cm or more) in men aged 65 to 75 who have ever smoked (current and former smokers) leads to decreased AAA-specific mortality.  The USPSTF found that there is good evidence that abdominal ultrasonography, performed in a setting with adequate quality assurance (i.e., in an accredited facility with credentialed technologists), is an accurate screening test for AAA.  The USPSTF also identified, however, important harms of screening and early treatment, including an increased number of surgeries with associated clinically-significant morbidity and mortality, and short-term psychological harms.  Based on the moderate magnitude of net benefit, the USPSTF concluded that the benefits of screening for AAA in men aged 65 to 75 who have ever smoked outweigh the harms.

The USPSTF made no recommendation for or against screening for AAA in men aged 65 to 75 who have never smoked.  Although the USPSTF found good evidence that screening for AAA in men aged 65 to 75 who have never smoked leads to decreased AAA-specific mortality, there is a lower prevalence of large AAAs in men who have never smoked compared with men who have ever smoked; thus, the USPSTF determined that the potential benefit from screening men who have never smoked is small.  The USPSTF also weighed the harms of screening and early treatment, and concluded that the balance between the benefits and harms of screening for AAA is too close to make a general recommendation in this population.

The USPSTF recommended against routine screening for AAA in women.  The USPSTF explained that, because of the low prevalence of large AAAs in women, the number of AAA-related deaths that can be prevented by screening this population is small.  The USPSTF concluded that the harms of screening women for AAA outweigh the benefits.

The USPSTF reported that one-time screening to detect an AAA using ultrasonography is sufficient.  They concluded that there is negligible health benefit in re-screening those who have normal aortic diameter on initial screening.  The USPSTF concluded that, for most men, 75 years may be considered an upper age limit for screening.  Patients can not benefit from screening and subsequent surgery unless they have a reasonable life expectancy.  The USPSTF explained that increased presence of co-morbidities for people aged 75 and older decreases the likelihood that they will benefit from screening.

It is generally recommended that patients with AAA of 5.5 cm or greater seek open surgical repair.  Open surgical repair for an AAA of at least 5.5 cm leads to an estimated 43 % reduction in AAA-specific mortality in older men who undergo screening.  However, there is no current evidence that screening reduces all-cause mortality in this population.

The USPSTF reported that, in men with intermediate-sized AAAs (4.0 to 5.4 cm), periodic surveillance offers comparable mortality benefit to routine elective surgery with the benefit of fewer operations.  The USPSTF found no evidence to support the effectiveness of any intervention in those with small AAAs (3.0 to 3.9 cm); the USPSTF noted, however, that, there are expert opinion-based recommendations in favor of periodic repeat ultrasonography for these patients.

Repeat abdominal ultrasound testing every 6 months has been recommended for men with abdominal aortic aneurysms greater than 4 cm in diameter, and every 2 years for men with smaller abdominal aortic aneurysms (Lederle, 2003).

Color flow duplex ultrasound scanning has been used as an surveillance modality for clinically significant endoleaks in patients who have undergone endovascular repair of AAAs.  Sun (2006) systematically reviewed the findings of diagnostic value of color duplex ultrasound (US) in the follow-up of endovascular repair of AAAs.  Studies comparing the diagnostic accuracy of color duplex US with that of computed tomographic (CT) angiography were included, and analysis was performed of the detection of endoleaks and measurement of aneurysm diameter.  A total of 21 studies (39 separate comparisons) met the criteria and were included for analysis.  Pooled estimates of sensitivity, specificity, positive-predictive value (PPV), negative-predictive value (NPV), and accuracy of color duplex US compared with CT angiography (with 95 % confidence interval [CI]) were 66 % (52 to 81 %), 93 % (89 to 97 %), 76 % (65 to 87 %), 90 % (86 to 95 %), and 91 % (86 to 97 %), respectively, for unenhanced color duplex US; and 81 % (52 to 100 %), 82 % (68 to 97 %), 58 % (26 to 90 %), 95 % (87 to 100 %), and 98 % (91 to 100%), respectively, for enhanced color duplex US.  The sensitivity in the detection of endoleak was significantly improved with contrast material-enhanced color duplex US compared with unenhanced color duplex US (p < 0.05); however, no significant difference was found regarding the specificity, PPV, NPV, and accuracy between unenhanced and enhanced color duplex US (p > 0.05).  Color duplex US was insensitive in measurement of aneurysm diameter compared with CT angiography in most situations.  The authors concluded that color duplex US is not as accurate as CT angiography and can not replace CT angiography in the follow-up of endovascular aortic repair of AAAs.  However, the use of contrast material-enhanced color duplex US resulted in improvement of diagnostic accuracy in the detection of endoleak and warrants further study.

Kim et al (2007) estimated the benefits, in terms of AAA-related and all-cause mortality, and cost-effectiveness of ultrasonography screening for AAA in a group that was invited to screening compared with a group that was not invited at a mean 7-year follow-up.  Population-based sample of 67,770 men aged 65 to 74 years were included in this analysis.  Patients with an AAA detected at screening had surveillance and were offered surgery after pre-defined criteria were met.  Mortality data were obtained after flagging on the national database.  Unit costs obtained from large samples were applied to individual event data for the cost analysis.  The hazard ratio was 0.53 (95 % CI: 0.42 to 0.68) for AAA-related mortality in the group invited for screening.  The rupture rate in men with normal results on initial ultrasonography has remained low: 0.54 rupture (CI: 0.25 to 1.02 ruptures) per 10,000 person-years.  In terms of all-cause mortality, the observed hazard ratio was 0.96 (CI: 0.93 to 1.00).  At the 7-year follow-up, cost-effectiveness was estimated at $19,500 (CI: $12,400 to $39,800) per life-year gained based on AAA-related mortality and $7,600 (CI: $3,300 to infinity) per life-year gained based on all-cause death.  Inclusion of deaths from aortic aneurysm at an unspecified site, which may include some thoracic aortic aneurysms, may have under-estimated the treatment effect.  The authors concluded that these findings from a large, pragmatic randomized trial showed that the early mortality benefit of screening ultrasonography for AAA is maintained in the longer term and that the cost-effectiveness of screening improves over time.

In a Cochrane review on screening for AAA, Cosford and Leng (2007) concluded that there is evidence of a significant reduction in mortality from AAA in men aged 65 to 79 years who undergo ultrasound screening.  However, there is insufficient evidence to demonstrate benefit in women.

Eckstein and colleagues (2009) stated that ultrasonography of the abdominal aorta is a safe and technically simple method of detecting AAAs.  These investigators performed a meta-analysis of population-based, randomized controlled trials (RCTs) of ultrasonographic screening for the detection of AAA.  A total of 4 RCTs showed that ultrasonographic screening was associated with a significant lowering of AAA-related mortality in men aged 65 to 80 after it had been performed for 3 to 5 years (risk reduction 44 %, odds ratio [OR] 0.56, 95 % CI: 0.44 to 0.72) and after it had been performed for 7 to 15 years (risk reduction 53 %, OR 0.47, 95 % CI: 0.25 to 0.90).  Screening of AAA was also associated with a significant lowering of the overall mortality after 7 to 15 years, but not in the first 5 years.  Ultrasonographic screening led to a significant increase in the number of elective AAA operations performed and to a 50 % reduction of the number of emergency operations for ruptured AAA.  The authors concluded that ultrasonographic screening for AAA is a technically simple diagnostic test that is associated with a major reduction of AAA-related mortality.  In view of the higher prevalence of AAA among the elderly, it is recommended that all men aged 65 or older and all men and women with a family history of AAA should be systematically screened.

Koelemay et al (2009) noted that the evidence-based guideline "Diagnosis and treatment of abdominal aortic aneurysm" is applicable to all patients with an atherosclerotic fusiform or ruptured AAA.  An AAA with a diameter less than 5.5 cm is treated conservatively and monitored by sonographic surveillance.  All patients are advised secondary prevention with anti-platelet therapy, statin therapy, treatment of hypertension and smoking cessation.  Depending on co-morbidity, the indication for an operation is an AAA diameter of 5.5 cm.  The anatomical characteristics of the AAA guides the choice for an open operation or endovascular aneurysm repair (EVAR).  In view of the lower peri-operative mortality, EVAR is the treatment of choice.  Due to the high prevalence of AAA in siblings of patients with an AAA, the screening of these family members should be considered.