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Draft Research Plan

Draft Research Plan for Abdominal Aortic Aneurysm: Primary Care Screening

This opportunity for public comment expired on September 6, 2017 at 8:00 PM EST

Note: This is a Draft Research Plan. This draft is distributed solely for the purpose of receiving public input. It has not been disseminated otherwise by the USPSTF. The final Research Plan will be used to guide a systematic review of the evidence by researchers at an Evidence-based Practice Center. The resulting Evidence Review will form the basis of the USPSTF Recommendation Statement on this topic.

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.

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In an effort to maintain a high level of transparency in our methods, we open our draft Research Plans to a public comment period before we publish the final version.

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Draft: Proposed Analytic Framework

 

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).

 

Abbreviation: AAA=abdominal aortic aneurysm.

 

Text Description

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).

Draft: Proposed Key Questions to Be Systematically Reviewed

  1. 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?
    1. Do the effects of one-time screening for AAA vary among subpopulations (i.e., by sex, smoking status, age, family history, or race/ethnicity)?
  2. 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?
    1. Do the effects of rescreening for AAA vary among subpopulations (i.e., by sex, smoking status, age, family history, or race/ethnicity)?
    2. Do the effects of rescreening for AAA vary by the time interval between screenings?
  3. What are the harms of one-time and repeated screening for AAA?
  4. 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)?
    1. Do the effects of treatment vary among subpopulations (i.e., by sex, smoking status, age, family history, or race/ethnicity)?
  5. 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)?

Draft: Proposed Contextual Questions

Contextual questions will not be systematically reviewed and are not shown in the Analytic Framework.

  1. Are there externally validated risk models for screening for AAA?   
  2. Does the epidemiology or overall effectiveness of treatment of AAA differ by age, sex, smoking status, or family history?
  3. Does screening yield differ based on screening strategy (e.g., high-risk vs. low-risk populations)?

Draft: Proposed Research Approach

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
Current as of: August 2017

Internet Citation: Draft Research Plan: Abdominal Aortic Aneurysm: Primary Care Screening . U.S. Preventive Services Task Force. November 2017.
https://www.uspreventiveservicestaskforce.org/Page/Document/draft-research-plan/abdominal-aortic-aneurysm-primary-care-screening

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