Screening for Abdominal Aortic Aneurysm

Summary

A Cochrane review [Abstract] 1 included 4 studies with a total of 137 233 male and female subjects (only one study included women, n=9 342). Results for men and women were analysed separately. Three to five years after screening there was no significant difference in all-cause mortality between screened and unscreened groups for men or women (for men OR 0.95, 95% CI 0.85 to 1.07; for women OR 1.06, 95% CI 0.93 to 1.21). There was a significant decrease in mortality from AAA in men (OR 0.60, 95% CI 0.47 to 0.78), but not for women (OR 1.99, 95% CI 0.36 to 10.88). In this analysis mortality includes death from rupture and from emergency or elective surgery for aneurysm repair. There was also a decreased incidence of ruptured aneurysm in men (OR 0.45, 95% CI 0.21 to 0.99) but not in women (OR 1.49, 95% CI 0.25 to 8.94). There was a significant increase in surgery for AAA in men (OR 2.03, 95% CI 1.59 to 2.59). This was not reported in women. There were no data on life expectancy, complications of surgery or subjective quality of life. The MASS study has published a cost effectiveness analysis of the benefits of AAA screening. The study identified 47 fewer deaths over 4 years due to AAA, at an additional cost of £2.2 million. This equated to £28,400 per life year gained, and approximately £36,000 per QALY (Quality Adjusted Life Year). After 10 years this is estimated to fall to about £8,000 per life year gained. The Viborg trial identified outline hospital costs with an estimate of costs outside hospital. They derived a figure of DKK 7540 per life year saved (£1 = 12 DKK).

A systematic review 2 included 4 randomized studies with a total of 125 576 men aged > 65 years comparing 1-time ultrasound screening vs. no screening. Screening was associated with reduced short-term (3-5 years) AAA mortality (RR 0.57, 95% CI 0.44 to 0.72; number needed to screen [NNS] 796), long-term (13-15 years) AAA mortality (RR 0.66, 95% CI 0.47 to 0.93, statistical heterogeneity I² =80%; NNS 311), and reduced AAA rupture rate in short (RR 0.52, 95% CI, 0.35 to 0.79, statistical heterogeneity I² =58%; NNS 606) and long-term follow-up (RR 0.65, 95% CI 0.51 to 0.82, statistical heterogeneity I² =56%; NNS 264). The effect on all-cause mortality was nonsignificant for short-term follow-up (RR 0.94, 95% CI 0.88 to 1.02, statistical heterogeneity I² =81%) and marginally significant for long-term follow-up (RR 0.99, 95% CI 0.98 to 1.00). One-time AAA screening was associated with an increase in the number of elective AAA-related procedures.

A systematic review 3 included the same 4 studies as the Cochrane review. Conclusions were similar. The review also evaluated repeated screening following negative results on ultrasonography. Overall, a single negative ultrasonography screen at age 65 years appeared to virtually exclude any future risk of AAA rupture or death.