Screening for abdominal aortic aneurysm in asymptomatic adults
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BACKGROUND: This report was produced for the Canadian Task Force on Preventive Health Care to provide guidelines on screening for abdominal aortic aneurysm (AAA) with ultrasound scan. PURPOSE: The aim of this systematic review is to examine the evidence on benefits and harms of AAA screening. SEARCH STRATEGY: This systematic review considered studies from the most recent United States Preventive Services Task Force review on AAA screening and passed through the screening process with citations identified in our search up to April 2015 (PROSPERO Registration #CRD42015019047). RESULTS: For benefits of one-time AAA screening in men compared with controls, pooled analyses from four randomized controlled trials with moderate quality evidence showed significant reductions in AAA-related mortality and AAA rupture rate up to 13 to 15 years of follow-up with 42% reduction (risk ratio [RR], 0.58; 95% confidence interval [CI], 0.39-0.88; number needed to screen = 212) and 38% reduction (RR, 0.62; 95% CI, 0.45-0.86; number needed to screen = 200), respectively. The effect of on all-cause mortality was marginally significant for longer follow-up. The Chichester trial examined the benefits of one-time AAA screening in women and found no significant differences between screening and control arms for up to 10 years of follow-up (RR, 0.88; 95% CI, 0.72-1.07). For consequences of one-time AAA screening in men compared with controls, there was a significant increase in the total number of AAA-related procedures over a follow-up of 13 to 15 years (2.16 times more likely) compared with controls. For harms of one-time AAA screening, no significant differences were observed in 30-day postoperative mortality for elective and emergency operations with compared control groups. Evidence from the Multicenter Aneurysm Screening Study trial using 13-year follow-up data showed that one-time AAA screening with ultrasound scan was potentially associated with an overdiagnosis of 45% (95% CI, 42%-47%) among screen-detected men. CONCLUSIONS: Population-based screening for AAA with ultrasound scan in asymptomatic men aged 65 years and older showed statistically significant reductions in AAA-related mortality and rupture and, hence, avoids unnecessary AAA-related deaths. The current evidence showed no benefit of one-time AAA screening in woman. Limited evidence is available on the benefits of repeat AAA screening and targeted screening approaches based on risk factors for AAA. Future research should explore the differential benefits of AAA screening based on risk factors that increase risk for developing AAA.