Abdominal aortic aneurysm: the case where a single ultrasound reduced rupture deaths in four trials
The essentials
- Four randomized trials with 134,271 people, mostly men aged 65 or older, showed that offering an aortic ultrasound cut abdominal aortic aneurysm deaths by 35% (Peto odds ratio 0.65; 95% CI 0.57 to 0.74).[1]
- 305 men had to be invited to screening to prevent one aneurysm death, and 246 to prevent one rupture.[1]
- It did not change all-cause mortality (RR 0.99) and there were about 40% more operations in the invited groups, with overtreatment that is hard to estimate.[1]
- It is an ultrasound aimed at a single vessel in a specific group; it is not a whole-body ultrasound.[1]
The case: an aneurysm that gives no warning
An abdominal aortic aneurysm (AAA) is a widening of the main artery of the abdomen to 3.0 cm or more. The US Preventive Services Task Force (USPSTF) notes that most cause no symptoms until they rupture, and that the risk of death with a rupture is as high as 81%.[1]
That makes it a candidate for screening: a person can have an aneurysm without knowing it, and finding it in time allows it to be monitored or repaired before it ruptures. The test is a duplex abdominal ultrasound, with no radiation, with a sensitivity of 94 to 100% and a specificity of 98 to 100%.[1]
What the trials showed
The USPSTF evidence report (Guirguis-Blake, JAMA, 2019) pooled four randomized trials with 134,271 participants, almost all men aged 65 or older: MASS (67,800), Western Australia (38,480), Chichester (15,382, the only one that included women) and Viborg (12,639). In all of them, one group was invited to a single ultrasound and the other was not. Follow-up reached 13 years for aneurysm mortality and 15 years for all-cause mortality.[1][2]
| Measure | Result |
|---|---|
| Aortic aneurysm deaths | Peto odds ratio 0.65 (95% CI 0.57 to 0.74), a 35% reduction |
| People to screen to prevent 1 aneurysm death | 305 (95% CI 248 to 411) |
| Ruptures | Peto odds ratio 0.62 (95% CI 0.55 to 0.70); 246 to screen to prevent 1 |
| Emergency operations | Peto odds ratio 0.57 (95% CI 0.48 to 0.68) |
| All-cause mortality | RR 0.99 (95% CI 0.98 to 1.00): no significant effect |
| Total operations | About 40% more in the invited groups (Peto odds ratio 1.44; 95% CI 1.34 to 1.55) |
The results were not the same in every trial: MASS (hazard ratio 0.58) and Viborg (0.34) showed a clear reduction in aneurysm deaths, but Chichester and Western Australia did not show a significant benefit.[1]
The limits
- Most clearly for men aged 65 to 75 who have smoked. The USPSTF recommends a one-time ultrasound, with moderate net benefit in men who ever smoked and small net benefit in those who never did.[1]
- Women: the USPSTF found insufficient evidence in women aged 65 to 75 who smoked or have a family history, and recommends against screening those who never smoked and have no family history.[1]
- After a normal ultrasound: in men with an initially normal ultrasound (aorta under 3 cm), aneurysm mortality over 5 to 12 years was low, under 3%.[1]
What about whole-body ultrasound?
The trials evaluated an ultrasound aimed at the aorta in a risk group, not a whole-body study. That an aortic ultrasound works in older men who smoked does not show that an ultrasound that checks many organs benefits a healthy person. If you are interested, the imaging page explains what each study includes, and your doctor can tell you whether aortic screening applies to you.
Frequently asked questions
Who should get an aortic ultrasound?
The USPSTF recommends a one-time ultrasound in men aged 65 to 75 who have smoked, and leaves it as an individual decision for those who never smoked. Your doctor weighs your risk factors.[1]
Does it hurt or expose me to radiation?
It is an abdominal ultrasound: noninvasive and with no radiation.[1]
Does screening make the men who receive it live longer?
It reduced aneurysm deaths, but no significant change was seen in all-cause mortality.[1]
References
- US Preventive Services Task Force. Abdominal aortic aneurysm: screening. Final recommendation statement. December 10, 2019. Open the source
- Guirguis-Blake JM, Beil TL, Senger CA, Coppola EL. Primary care screening for abdominal aortic aneurysm: updated evidence report and systematic review for the US Preventive Services Task Force. JAMA. 2019;322(22):2219-2238. Open the source
Keep reading
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