Draft Research Plan
Abdominal Aortic Aneurysm: Screening
August 10, 2017
Recommendations made by the USPSTF are independent of the U.S. government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.
Abbreviation: AAA=abdominal aortic aneurysm.
Figure 1 is the analytic framework that depicts the five Key Questions to be addressed in the systematic review. The figure illustrates how screening for abdominal aortic aneurysm (AAA) may result in improved health outcomes, including reducing AAA-specific and all-cause mortality, as well as aneurysm rupture rate (KQ1). Additionally, the figure depicts the effects of rescreening for AAA on health outcomes or AAA incidence in a previously screened, asymptomatic population (KQ2), as well as harms associated with one-time and repeated screening (KQ3). Further, the figure illustrates how treating small AAAs (i.e., aortic diameter of 3.0 to 5.4 cm) with pharmacotherapy or surgery effects treatment-relevant intermediate health outcomes (KQ4) and what harms are associated with these treatments (KQ5).
- What are the effects of one-time screening for abdominal aortic aneurysm (AAA) on health outcomes in an asymptomatic population age 50 years or older?
- Do the effects of one-time screening for AAA vary among subpopulations (i.e., by sex, smoking status, age, family history, or race/ethnicity)?
- What are the effects of rescreening for AAA on health outcomes or AAA incidence in a previously screened, asymptomatic population without AAA on initial screening?
- Do the effects of rescreening for AAA vary among subpopulations (i.e., by sex, smoking status, age, family history, or race/ethnicity)?
- Do the effects of rescreening for AAA vary by the time interval between screenings?
- What are the harms of one-time and repeated screening for AAA?
- What are the effects of treatment (pharmacotherapy or surgery) on treatment-relevant, intermediate health outcomes in an asymptomatic, screen-detected population with small AAAs (i.e., aortic diameter of 3.0 to 5.4 cm)?
- Do the effects of treatment vary among subpopulations (i.e., by sex, smoking status, age, family history, or race/ethnicity)?
- What are the harms of treatment in an asymptomatic, screen-detected population with small AAAs (i.e., aortic diameter of 3.0 to 5.4 cm)?
Contextual questions will not be systematically reviewed and are not shown in the Analytic Framework.
- Are there externally validated risk models for screening for AAA?
- Does the epidemiology or overall effectiveness of treatment of AAA differ by age, sex, smoking status, or family history?
- Does screening yield differ based on screening strategy (e.g., high-risk vs. low-risk populations)?
The Proposed Research Approach identifies the study characteristics and criteria that the Evidence-based Practice Center will use to search for publications and to determine whether identified studies should be included or excluded from the Evidence Review. Criteria are overarching as well as specific to each of the key questions (KQs).
| Included | Excluded | |
|---|---|---|
| Populations | KQs 1–3: Asymptomatic adult population
KQs 4, 5: Asymptomatic adult population with small AAAs (i.e., aortic diameter of 3.0 to 5.4 cm) |
KQs 1–3: Patients experiencing symptoms related to AAA
KQs 4, 5: Patients experiencing symptoms related to AAA; populations with AAAs with an aortic diameter larger than 5.4 cm or smaller than 3.0 cm |
| Setting | Studies conducted in primary care or other settings with a comparable population to primary care (e.g., general unselected population for screening [KQs 1, 3]) | |
| Disease/condition | AAA (with an aortic diameter ≥3.0 cm) | |
| Interventions | KQs 1–3: Screening with ultrasound
KQs 4, 5: Treatment with pharmacotherapy (e.g., statins, angiotensin converting enzyme inhibitors, antibiotics) or surgical intervention |
KQs 1–3: Screening with physical examination, computed tomography, or magnetic resonance imaging |
| Comparisons | KQs 1, 3: One-time screening compared with no screening
KQs 2, 3: Repeat screening compared with no rescreening KQ 4: Treatment (pharmacotherapy or surgery) compared with surveillance or usual care |
KQs 4, 5: Comparative effectiveness of treatments
KQ 2: Comparison of surveillance interval |
| Outcomes | KQs 1, 2: All-cause mortality, aneurysm-related mortality, aneurysm rupture rate, and quality of life
KQ 3: Anxiety and downstream procedures related to false-positive results KQ 4: AAA annual growth rate, all-cause mortality, aneurysm-related mortality, aneurysm rupture rate, and quality of life KQ 5: Harms (i.e., serious adverse events from pharmacotherapy or surgery) |
|
| Study Designs | KQs 1, 4: Randomized, controlled trials
KQs 2, 3: Randomized, controlled trials; large cohort studies (sample size >1,000) KQ 5: Randomized, controlled trials; large cohort studies (sample size >1,000); vascular surgery registries |
KQs 1, 4: Case-control, cross-sectional, and cohort studies; editorials, letters, and opinions; cost studies
KQs 2, 3: Case-control and cross-sectional studies; editorials, letters, and opinions; cost studies |
| Countries | Studies conducted in countries categorized as "Very High" on the 2016 Human Development Index (as defined by the United Nations Development Programme) | Studies conducted in countries that are not categorized as "Very High" on the 2016 Human Development Index |
| Language | English only | Languages other than English |
| Quality | Fair- and good-quality studies | Poor-quality studies |