Abdominal Aortic Aneurysm: Screening -- Women Who Have Never Smoked


General

Grade: D The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits. Discourage the use of this service.

Specific Recommendations

The USPSTF recommends against routine screening for AAA in women who have never smoked.

Frequency of Service

No information available.

Risk Factor Information

No information available.


Clinical

Patient Population Under Consideration

This recommendation applies to asymptomatic adults age 50 years and older.

Assessment of Risk

Smoking Status

Consuming 100 or more cigarettes is commonly used in epidemiologic literature to define an “ever-smoker.” However, the randomized trials of screening for AAA did not gather specific data about participants' smoking histories. Occasional tobacco use for a short time in the past (for example, occasional “social” smoking as an adolescent or young adult) is unlikely to have a pronounced biological effect, and the odds ratio (OR) of developing a large (≥5.0 cm) AAA is actually less than 1.0 for prior smokers who have quit for at least 10 years. However, observational studies have found that even a relatively modest smoking history (for example, smoking a half-pack or less per day for fewer than 10 years) does increase the likelihood of developing a large AAA.

Screening in Men Ages 65 to 75 Years Who Have Never Smoked

Despite the demonstrated benefits of screening for AAA in men overall, the lower prevalence of AAA in male never-smokers versus male ever-smokers suggests that clinicians should consider a patient's risk factors and the potential for harm before screening for AAA rather than routinely offering screening to all male never-smokers. Important risk factors for AAA include older age and a first-degree relative with an AAA; other risk factors include a history of other vascular aneurysms, coronary artery disease, cerebrovascular disease, atherosclerosis, hypercholesterolemia, obesity, and hypertension. Factors associated with a reduced risk for AAA include African American race, Hispanic ethnicity, and diabetes.

Suggestions for Practice Regarding the I Statement

Screening in Women Ages 65 to 75 Years Who Have Ever Smoked

Potential Preventable Burden

A screening study in Sweden found that the prevalence of AAA in women age 70 years was low (0.8%) for ever-smokers but increased to 2.0% for current smokers. A meta-analysis of individual-patient data found that women have a higher risk than men for AAA rupture at the same diameter (hazard ratio [HR], 3.76 [95% CI, 2.58 to 5.47]). However, AAA-associated deaths occur at an older age in women (at a time of increased competing causes of death and a declining benefit–risk ratio for operative interventions), with 70% of deaths occurring after age 80 years in women compared with fewer than 50% in men. In the only screening RCT that included women, most screen-detected AAAs in women were small (3.0 to 3.9 cm) and AAA-specific mortality was low in screened and unscreened women (<0.2%) after 10 years.

Potential Harms

Four RCTs (primarily done in men) showed that screening for AAA doubled the rate of AAA-associated surgeries, largely driven by an increase in elective surgeries. Most screen-detected AAAs were below the 5.5-cm threshold for immediate repair. This finding generally results in long-term or lifelong surveillance and is probably associated with some amount of overtreatment, although the magnitude of this burden is difficult to quantify.

Most screening trials reported an associated decrease in emergency AAA repairs and a reduced 30-day mortality rate associated with emergency surgery in populations invited to screen, although mortality associated with elective surgery was not reduced. Operative mortality associated with AAAs is higher in women than in men (7% vs. 5% for open repair and 2% vs. 1% for endovascular repair, respectively).

Costs

In addition to the cost of ultrasonography screening (approximately $100), the estimated potential associated cost of elective surgery to repair a screen-detected AAA ranges from $37,000 to $43,000. Potential opportunity costs also may arise, because screening may take the place of other preventive activities that may be of greater benefit to the patient.

Current Practice

Screening for AAA is provided as part of the “welcome-to-Medicare visit” for women who have a family history of AAA. However, the evidence is insufficient to accurately characterize current practice patterns related to screening for AAA in women.

A retrospective analysis from 2000 to 2010 used the National Inpatient Sample, a database that has a stratified 20% random sample of all nonfederal inpatient hospital admissions in the United States. This analysis found that women are more likely than men to have open surgery versus endovascular aneurysm repair (EVAR) for unruptured AAA (24% vs. 17%, respectively), potentially because of issues with access to the iliac artery (that is, smaller artery size) that may preclude endovascular management.

A retrospective review of 4,026 AAA repairs in the Vascular Study Group of New England database (a voluntary registry from 30 academic and community hospitals in six New England states) reported that women were more likely than men to have open surgery versus EVAR and to be older and have smaller aortic diameters at the time of repair. Postoperative complications were higher in women than in men after elective EVAR or open repair, including emergency reoperations, dysrhythmias, leg ischemia or emboli, bowel ischemia, or need for discharge to another medical facility rather than home.

Screening Methods

Conventional abdominal duplex ultrasonography was the primary method used in the available trials of AAA screening. Primary care physicians and vascular surgeons widely accept abdominal duplex ultrasonography as the standard approach. Screening with ultrasonography is noninvasive and easy to do and has high sensitivity (94% to 100%) and specificity (98% to 100%) for detecting AAA. In addition, it has shown high rates of reproducibility, does not expose patients to radiation, and is relatively low-cost.

The use of handheld, portable ultrasonography devices in clinician office settings has been proposed as an alternative approach to conventional abdominal duplex ultrasonography done in the radiology setting. Several small observational studies suggest that in-office handheld ultrasonography has reasonable sensitivity and specificity for AAA detection compared with conventional ultrasonography. However, it has not been formally evaluated in a clinical trial.

Screening Intervals

Evidence is adequate to support one-time screening in men who have ever smoked. All of the population-based RCTs of AAA screening used a one-time screening approach, and several fair- to good-quality prospective cohort studies show that AAA-associated mortality over 5 to 12 years is low (0.0% to 2.4%) in men with initially normal results on ultrasonography.

Treatment

In the available screening trials, immediate referral for open surgery in patients with large AAAs (≥5.5 cm) and conservative management via repeated ultrasonography every 3 to 12 months for smaller AAAs (3.0 to 5.4 cm) achieved the observed AAA-related mortality benefit. Surgical referral of smaller AAAs was reserved for AAAs that grew rapidly (>1.0 cm per year) or reached a threshold of 5.5 cm or larger on repeated ultrasonography.

Although early open surgery for smaller AAAs reduces the risk for rupture compared with surveillance, it does not reduce AAA-specific or all-cause mortality. Endovascular aneurysm repair is an alternative to open surgery. As with open surgery, early EVAR did not differ from surveillance for smaller AAAs in all-cause or AAA-related mortality in randomized trials that evaluated these interventions. Unlike early open surgery, early EVAR does not reduce the incidence of AAA rupture.

Pharmacotherapy has been proposed to slow the growth of smaller AAAs. Short-term treatment with antibiotics or β-blockers does not seem to reduce AAA growth, and the trials were underpowered to draw conclusions about effects on health outcomes.


Other Considerations

Research Needs and Gaps

Although evidence shows that women who smoke are at increased risk for AAA compared with nonsmoking women, evidence that screening this population confers a net benefit is insufficient. The same is true for men and women with a family history of AAA. Ideally, appropriately powered RCTs with planned a priori subgroup analyses would be done to answer these critical questions. In the absence of new trial data, high-quality modeling studies should be done to determine whether screening is beneficial in women who smoke or in men and women with a family history of AAA.

Several risk-scoring tools have been developed and, if prospectively validated, could be used to identify patients most likely to benefit from screening. Thus, validation studies of these tools should be prioritized. Because of the importance of family history as a risk factor, the role of genetic markers of AAA development should be explored.

Alternative strategies to reduce AAA growth, such as antibiotics, statins, or other novel pharmacologic agents, need to be further explored. Interventions to address modifiable risk factors (particularly smoking) may be worth considering. Effective strategies for smoking cessation may improve the care of patients with small AAAs. Seven ongoing RCTs are evaluating pharmacotherapeutic effects on small AAAs; however, the outcome in most trials is aneurysmal growth, and the trials are underpowered to detect changes in health outcomes. Appropriately powered studies that can assess health outcomes should evaluate whether such treatments are viable options in preventing death.

One screening RCT, the VIVA (Viborg Vascular) trial, is currently evaluating the effectiveness of combined screening for AAA, peripheral artery disease, and hypertension in 50,000 men ages 65 to 74 years; results are not expected until after 2018. Participants who screen positive for AAA or peripheral artery disease are advised on exercise, low-fat diet, and smoking cessation and are managed with statins and aspirin. They receive annual surveillance for AAA and peripheral artery disease, and those with an AAA measuring 5.0 cm or larger are referred for surgery.

Followup will occur at 3.5, 10, and 15 years for the primary outcome of all-cause mortality. Secondary outcomes include cardiovascular mortality, AAA-specific mortality, AAA prevalence and progression, health-related quality of life, and cost-effectiveness. This study may also provide evidence as to whether a screen-detected AAA can be used as a marker and improve outcomes for other cardiovascular diseases.

Rationale

No information available.


Others

The American College of Cardiology and the American Heart Association jointly recommend one-time screening for AAA with physical examination and ultrasonography in men ages 65 to 75 years who have ever smoked and in men age 60 years or older who are the sibling or offspring of a person with AAA. These organizations do not recommend screening for AAA in men who have never smoked or in women. The Society for Vascular Surgery recommends one-time ultrasonography screening for AAA in men age 55 years or older with a family history of AAA, all men age 65 years or older, and women age 65 years or older who have smoked or have a family history of AAA. The American College of Preventive Medicine recommends one-time screening in men age 65 to 75 years who have ever smoked; it does not recommend routine screening in women.The Canadian Society for Vascular Surgery recommends ultrasonography screening for AAA in men age 65 to 75 years who are candidates for surgery and willing to participate. In individualized cases, some women older than 65 years with multiple risk factors for AAA (smoking history, cerebrovascular disease, or family history) may be considered for screening. The European Society for Vascular Surgery recommends that men should be screened for AAA with a single ultrasonography at age 65 years, but screening should be considered at an earlier age in men at higher risk (for example, those who smoke, have other cardiovascular disease, or have a family history). It notes that screening in older women generally does not reduce the incidence of aneurysm rupture but that screening women who smoke may require further investigation.


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