Therapeutics

Review: Ultrasonography screening reduces long-term abdominal aortic aneurysm–related mortality

Guirguis-Blake JM, Beil TL, Senger CA, Whitlock EP. Ultrasonography screening for abdominal aortic aneurysms: a systematic evidence review for the U.S. Preventive Services Task Force. Ann Intern Med. 2014;160:321-329.

Clinical impact ratings: F ★★★★★★✩ C ★★★★★✩✩ Question

Source of funding: Agency for Healthcare Research and Quality.

In asymptomatic adults, what are the benefits and harms of ultrasonography screening for abdominal aortic aneurysms (AAAs)?

For correspondence: Dr. J.M. Guirguis-Blake, University of Washington, Tacoma, WA, USA. E-mail [email protected]. ■

Review scope

Commentary

Included English-language studies of 1-time or repeated screening for AAAs with ultrasonography in asymptomatic adults in primary care. Studies rated as poor quality were excluded. Outcomes included AAA-related mortality, AAA rupture, and elective surgery.

Emergency surgery for ruptured AAAs has high intraoperative mortality, whereas elective surgery has an operative mortality < 5% in many centers (1). The risk for rupture is particularly high when AAA diameter is > 5.5 cm (2). Risk factors for AAA development and progression include male sex, increasing age, hypertension, hyperlipidemia, atherosclerosis, and smoking. Intense management of risk factors, particularly smoking, is considered helpful in conservatively managing AAA. In many countries, incidence of AAA is declining possibly due to associated reductions in smoking rates (3).

Review methods This was an update of a previous review. MEDLINE (2004 to Sep 2013), Database of Abstracts of Reviews of Effects and Cochrane Central Register of Controlled Trials (both 2004 to Jan 2013), and reference lists were searched for randomized controlled trials (RCTs) and cohort studies (≥ 1000 participants). Experts were contacted. 4 RCTs met selection criteria for effectiveness of 1-time screening (n = 137 214, mean age 68 to 73 y, 41% to 100% men, 2 fair quality, 2 good quality), 10 studies for effectiveness of repeated screening, and 7 studies for harms of 1-time and repeated screening. This abstract presents the RCT results for 1-time screening. Although pooled analyses were done, most had significant heterogeneity; therefore, the authors focused on the unpooled results.

The review by Guirguis-Blake and colleagues provides estimates for the benefits and risks associated with ultrasonography screening for AAAs, with patient follow-up, including surgery, adhering to the protocols used in the studies. Included trials had follow-up times ranging from 3.6 to 15 years, sufficient for assessing mortality outcomes. All-cause mortality was not affected by screening, but AAA-related mortality was reduced, with the number needed to screen to prevent an AAA-related death ranging from 144 to 289. Quality of life was not assessed, although the screening group had a higher rate of elective surgeries.

Main results

Since these included studies were completed, endovascular repairs have become more popular than open repairs, now comprising ≥ 80% of procedures (4). Endovascular repairs have been shown Conclusion to reduce 30-day postoperative AAA-related mortality but not In asymptomatic adults, ultrasonography screening for abdominal long-term AAA-related mortality (4). However, the technique is aortic aneurysms (AAAs) reduced AAA-related mortality in 2 trials, now frequently being used on small aneurysms (59% of procedecreased rupture in 1 trial, and increased elective surgery in 3 trials. dures in patients with AAA diameter < 5.5 cm), without supporting evidence of long-term efficacy and with Screening for abdominal aortic aneurysms (AAA) by ultrasonography vs the potential for unnecessary surgery and harm (5). usual care in asymptomatic adults (randomized controlled trials)* The main results are in the Table.

Outcomes

Trials†

AAA-related mortality‡

AAA rupture

Event rates At a median 3.6 to a mean 15 y Screening Usual RRR (95% CI) NNS (CI) care

MASS

0.7%

1.1%

42% (31 to 51)

213 (175 to 289)

Viborg

0.3%

0.9%

66% (43 to 80)

174 (144 to 268)

Chichester

1.6%

1.8%

12% (−30 to 40)

NS

Western Australian§

0.09%

0.13%

39% (−11 to 67)

NS

MASS

0.80%

1.4%

43% (33 to 51)

166 (140 to 216)

Chichester

1.8%

2.1%

13% (−25 to 39)

RRI (CI) Elective surgery

NS

NNH (CI)

MASS

1.8%

0.82% 117% (88 to 150)

105 (82 to 140)

Viborg

1.4%

0.70% 101% (41 to 188)

142 (77 to 350)

Chichester

1.4%

0.62% 119% (28 to 277)

135 (58 to 573)

*MASS = Multicentre Aneurysm Screening Study; NNS = number needed to screen; NS = not significant; other abbreviations defined in Glossary. RRR, RRI, NNS, NNH, and CI calculated from control event rates and hazard ratios or relative risks in article. †Sample sizes were MASS 67 800, Viborg 12 639, Chichester 15 775, and Western Australian 41 000. ‡AAA deaths plus all deaths within 30 d of AAA surgical repair. §Longest follow-up at a median 3.6 y.

JC6

© 2014 American College of Physicians

A.C. Felix Burden, MB, MD, FRCP Sandwell & West Birmingham Clinical Commissioning Group Birmingham, England, UK References 1. Earnshaw J, Mitchell D, Wyatt M, Lamont P, Naylor R. Remodelling of vascular (surgical) services in the UK. Eur J Vasc Endovasc Surg. 2012;44:465−7. 2. United Kingdom Small Aneurysm Trial Participants. Longterm outcomes of immediate repair compared with surveillance of small abdominal aortic aneurysms. N Engl J Med. 2002;346: 1445−52. 3. Sandiford P, Mosquera D, Bramley D. Trends in incidence and mortality from abdominal aortic aneurysm in New Zealand. Br J Surg. 2011;98:645-51. 4. Harris R, Sheridan S, Kinsinger L. Time to rethink screening for abdominal aortic aneurysm? Arch Intern Med. 2012;172: 1462-3. 5. Schanzer A, Greenberg RK, Hevelone N, et al. Predictors of abdominal aortic aneurysm sac enlargement after endovascular repair. Circulation. 2011;123:2848-55.

20 May 2014 | ACP Journal Club | Volume 160 • Number 10

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ACP Journal Club. Review: ultrasonography screening reduces long-term abdominal aortic aneurysm-related mortality.

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