Clinical Review & Education

JAMA Clinical Guidelines Synopsis

Screening for Abdominal Aortic Aneurysm Amber-Nicole Bird, MD; Andrew M. Davis, MD, MPH

GUIDELINE TITLE Screening for Abdominal Aortic Aneurysm DEVELOPER US Preventive Services Task Force RELEASE DATE June 24, 2014 PRIOR VERSION February 1, 2005 FUNDING SOURCE Agency for Healthcare Research and Quality

MAJOR RECOMMENDATIONS

• Screen 1 time for abdominal aortic aneurysm (AAA) with ultrasonography in men aged 65 to 75 years who have ever smoked (grade B). • Selectively offer screening for AAA in men aged 65 to 75 years who have never smoked (grade C). • There is too little evidence to recommend for or against screening for AAA in women who have ever smoked (grade I). • Do not screen for AAA in women who have never smoked (grade D).

TARGET POPULATION Asymptomatic adult men aged 65 to 75 years who have ever smoked

Summary of the Clinical Problem Abdominal aortic aneurysms are defined by an aortic anteroposterior diameter of 3 cm or more. 1 Population-based ultrasound screening and autopsy studies suggest a prevalence of any AAA in adults older than 50 years of 4% to 8% in men and 1% to 1.3% in women.2 Risk factors for AAA include age, male sex, having ever smoked, and family history of AAA. Abdominal aortic aneurysms often remain asymptomatic until rupture, a complication associated with mortality rates as high as 75% to 90%.2 Risk of rupture varies with aneurysm diameter (annual risk of 0% in aneurysms 3-3.9 cm, 1% in aneurysms 4-4.9 cm, and 11% in aneurysms 5-5.99 cm).3 Outcomes for emergency surgical intervention are also poor, with combined in-hospital and 30-day mortality rates of 40%.2 Ultrasonography is a safe and cost-effective screening tool that is highly sensitive (94%-100%) and specific (98%-100%) for detecting AAAs.1,2

Characteristics of the Guideline Source The guideline4 was written by the US Preventive Services Task Force (USPSTF), which is an independent volunteer panel of nonfederal experts in prevention and evidence-based medicine (Table). The task force is composed of primary care physicians and experts in methodology and health behavior. The guideline was developed in coordination with a systematic review sponsored by the Agency for Healthcare Research and Quality (AHRQ). A conflict of interest disclosure is completed by task force members prior to each meeting to provide information to AHRQ on potential financial, business/ professional, and intellectual conflicts of interest related to the topics addressed.

Evidence Base A systematic review was conducted to update the 2005 USPSTF guideline on screening for AAA and identified 68 studies of 1-time screening with ultrasonography for AAA in asymptomatic adults.1 Four large, population-based randomized trials were considered to 1156

be of good or fair quality (the Multicenter Aneurysm Screening Study [MASS] from the United Kingdom, Chichester [also UK], Viborg County [Denmark], and the Western Australian Screening Trial).3 Most of these studies enrolled predominantly white men older than 65 years. MASS was the largest, with more than 65 000 participants.1,5 Only the Chichester trial examined women, enrolling 9342 women aged 65 to 80 years.6

Benefits and Harms Resultsfromthe2highest-qualitytrials(MASSandViborg)foundarelative reduction in AAA-specific mortality of 42% to 66% in men aged 65 to 75 years who had ever smoked, beginning 3 years after the initial screening and persisting up to 15 years. In MASS, an invitation to screen was associated with decreased AAA rupture for up to 13 years (relative risk [RR], 0.57; 95% CI, 0.49-0.67; absolute risk reduction [ARR], 6/1000 screened]. The Viborg and MASS trials both showed fewer emergency surgeries in the screened groups at all time points, including pooled point estimates at the 13- to 15-year follow-up (RR, 0.42; 95% CI, 0.32-0.54; ARR, 2.6/1000 screened).3,5 The 2 fairqualitytrialsshowednoreductioninAAA-specificmortality.1,3 Menwho

Table. Guideline Rating Rating Standard

Rating

1. Establishing transparency

Good

2. Management of conflict of interest in the guideline development group

Good

3. Guideline development group composition

Good

4. Clinical practice guideline–systematic review intersection

Good

5. Establishing evidence foundations and rating strength for each of the guideline recommendations

Good

6. Articulation of recommendations

Fair

7. External review

Good

8. Updating

Good

9. Implementation issues

Fair

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JAMA Clinical Guidelines Synopsis Clinical Review & Education

had never smoked also had decreased AAA-specific mortality in the interventiongroup,butthedecreasedprevalenceofAAAsinthispopulation (2%) reduced the absolute screening benefit.1,2 The only study of screening in women (Chichester) noted a substantially decreased prevalence of AAA (1.3%) and found no difference in AAA-specific mortality and AAA rupture between screened and control groups.6 However, overall event rates were low, limiting statistical power for detection of differences. Other studies document a much lower prevalence of AAA in women who have never smoked (0.03%-0.6%).2,6 The principal harms associated with screening ultrasonography for AAA are related to AAA-related surgical intervention, potential need for lifelong surveillance, and potential effect on quality of life. Women were more likely to have AAAs that rupture at smaller diameters, and operative mortality for AAA repair appears higher in women, both for open repair (7% vs 5% in men) and endovascular repair (2% vs 1%).2,6 Moreover, fewer women undergo endovascular repair, likely because of anatomical constraints.7 There are few data on the influence of overdiagnosis of AAA. In the 4 randomized trials, more than 90% of AAAs identified during screening fell below the common cutoff for consideration of surgery (5.5 cm).1 Death from unrelated causes is common even for individuals with larger AAAs. One study of 24 000 autopsies found that of all individuals with AAAs, 75% died from causes unrelated to the AAA, as did nearly 60% of those with AAAs 5.1 cm or larger.1,2

Discussion There is convincing evidence of a reduction in AAA-specific mortality from1-timeultrasonographyscreeningamongmenaged65to75years who have ever smoked.1,2 No study has demonstrated a significant differenceinall-causemortalitybetweenscreenedandunscreenedmen.3 There is inadequate evidence to support general screening in women, as their low prevalence of AAA and worse outcomes associated with surgical intervention appear to outweigh any benefit.1,2 Controversy remains regarding AAA screening for men who have never smoked, women who have smoked or have other significant risk factors for AAA, and at-risk men outside the 65- to 75-year age range. Joint American College of Cardiology and American Heart Association guidelines extend screening recommendations to men ARTICLE INFORMATION Author Affiliations: University of Chicago, Chicago, Illinois. Corresponding Author: Amber-Nicole Bird, MD, University of Chicago, 5841 S Maryland Ave, MC 7082, Chicago, IL 60637 ([email protected]). Section Editors: Andrew M. Davis, MD, MPH, and Adam S. Cifu, MD, University of Chicago; and Edward H. Livingston, MD, Deputy Editor, JAMA. Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. REFERENCES 1. Guirguis-Blake JM, Beil TL, Senger CA, Whitlock EP. Ultrasonography screening for abdominal aortic aneurysms: a systematic evidence review for the US

aged 60 years or older who are first-degree relatives of individuals with known AAA but recommend against screening in women or in men who have never smoked.2 Both the Society for Vascular Surgery (SVS) and the European Society for Vascular Surgery recommend screening all men aged 65 years or older regardless of smoking history.2 The Canadian Society for Vascular Surgery (CSVS) recommends screening all men aged 65 to 75 years who are surgical candidates.2 Both the SVS and the CSVS make specific recommendations for screening women who are considered at high risk based on smoking or family history.1,2

Areas in Need of Future Study or Ongoing Research Future research is needed to better define the potential benefit of AAA screening in high-risk male and female populations. Populationbased screening programs in the United Kingdom and New Zealand have shown declining AAA prevalence, which raises important questions regarding the utility and cost-effectiveness of mass screening compared with more targeted screening interventions.1 Analysis of more than 3 million individuals aged 50 to 84 years receiving community-based AAA screening suggested that current guidelines would identify only 34% of AAAs 5.5 cm or larger, and a risk factor scoring tool was proposed to help identify screening candidates outside the current USPSTF guidelines.8 Further investigation will be required to validate such tools, to determine optimal rescreening intervals for aneurysms of various sizes, and to confirm the value of aggressive cardiovascular risk factor management once an AAA is identified.9 A second important research agenda concerns improving screening implementation and effectiveness. Recent screening rates in Sweden exceed 80%.9 In contrast, a large 1997 study in US Veterans Affairs hospitals found a screening rate of only 23%, and more recent data evaluating screening rates in Medicare beneficiaries following the implementation of the federal Screen for Abdominal Aortic Aneurysms Very Efficiently (SAAAVE) Act show that less than 15% of eligible patients undergo screening.10 Protocols that add best practice alerts to electronic medical records and screening for AAA during routine cardiac thoracic echocardiography have been explored. Carefully planned clinical decision support, audit and feedback, and public education offer promise in increasing AAA screening rates but can compete with other prevention priorities in primary care.

Preventive Services Task Force. Ann Intern Med. 2014;160(5):321-329. 2. LeFevre ML. Screening for abdominal aortic aneurysm: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2014; 161(4):281-290. 3. Guirguis-Blake JM, Beil TL, Sun X, et al. Primary Care Screening for Abdominal Aortic Aneurysm: A Systematic Evidence Review for the US Preventive Services Task Force. Rockville, MD: Agency for Healthcare Research and Quality; 2014:1-145. 4. US Preventive Services Task Force. Abdominal aortic aneurysm: screening. June 2014. http://www .uspreventiveservicestaskforce.org/Page/Topic /recommendation-summary/abdominal-aorticaneurysm-screening. Accessed February 13, 2015. 5. Thompson SG, Ashton HA, Gao L, et al. Final follow-up of the Multicentre Aneurysm Screening Study (MASS) randomized trial of abdominal aortic aneurysm screening. Br J Surg. 2012;99(12):16491656.

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6. Scott RA, Bridgewater SG, Ashton HA. Randomized clinical trial of screening for abdominal aortic aneurysm in women. Br J Surg. 2002;89(3): 283-285. 7. Dua A, Kuy S, Lee CJ, et al. Epidemiology of aortic aneurysm repair in the United States from 2000 to 2010. J Vasc Surg. 2014;59(6):1512-1517. 8. Greco G, Egorova NN, Gelijns AC, et al. Development of a novel scoring tool for the identification of large ⱖ5 cm abdominal aortic aneurysms. Ann Surg. 2010;252(4):675-682. 9. Björck M, Bown MJ, Choke E, et al. International update on screening for abdominal aortic aneurysms. Eur J Vasc Endovasc Surg. 2014:49(2): 113-115. 10. Hye RJ, Smith AE, Wong GH, et al. Leveraging the electronic medical record to implement an abdominal aortic aneurysm screening program. J Vasc Surg. 2014;59(6):1535-1542.

(Reprinted) JAMA March 17, 2015 Volume 313, Number 11

Copyright 2015 American Medical Association. All rights reserved.

Downloaded From: http://jama.jamanetwork.com/ by a New York University User on 05/30/2015

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Screening for abdominal aortic aneurysm.

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