Screening for abdominal aortic aneurysms: single centre randomised controlled trial

Abstract

Objective: To determine whether screening Danish men aged 65 or more for abdominal aortic aneurysms reduces mortality.

Design: Single centre randomised controlled trial.

Setting: All five hospitals in Viborg County, Denmark.

Participants: All 12,639 men born during 1921-33 and living in Viborg County. In 1994 we included men born 1921-9 (64-73 years). We also included men who became 65 during 1995-8.

Interventions: Men were randomised to the intervention group (screening by abdominal ultrasonography) or control group. Participants with an abdominal aortic aneurysm > 5 cm were referred for surgical evaluation, and those with smaller aneurysms were offered annual scans.

Outcome measures: Specific mortality due to abdominal aortic aneurysm, overall mortality, and number of planned and emergency operations for abdominal aortic aneurysms.

Results: 4860 of 6333 men were screened (attendance rate 76.6%). 191 (4.0% of those screened) had abdominal aortic aneurysms. The mean follow-up time was 52 months. The screened group underwent 75% (95% confidence interval 51% to 91%) fewer emergency operations than the control group. Deaths due to abdominal aortic aneurysms occurred in nine patients in the screened group and 27 in the control group. The number needed to screen to save one life was 352. Specific mortality was significantly reduced by 67% (29% to 84%). Mortality due to non-abdominal aortic aneurysms was non-significantly reduced by 8%. The benefits of screening may increase with time.

Conclusion: Mass screening for abdominal aortic aneurysms in Danish men aged 65 or more reduces mortality.

Fig 1

Flow of participants through trial

Fig 2

Kaplan-Meier estimates of mortality due to abdominal aortic aneurysm in Danish men aged 64-73 years. Difference between screened and control groups is P=0.003 (log rank test)

Fig 3

Kaplan-Meier estimates of total mortality in Danish men aged 64-73 years screened for abdominal aortic aneurysm and controls. Difference between screened and control groups is P=0.053 (log rank test)

Fig 4

Kaplan-Meier estimates of total mortality among attenders and non-attenders for screening for abdominal aortic aneurysm. Difference is P<0.001 (log rank test)