What is an Abdominal Aortic Aneurysm (or AAA)?

Abdominal aortic aneurysms (AAAs) are bulges in the main vessel carrying blood from the heart to the lower body. They occur predominantly in older people, more frequently in men than in women and in those who have ever smoked than never-smokers. AAAs increase in size over time, and can eventually rupture resulting in dangerous internal bleeding. Unfortunately around 4 out of 5 people who rupture their AAA do not survive. Furthermore, most AAAs do not cause any symptoms before they rupture.


What can be done to prevent this from happening?

An AAA is easy to detect by a simple ultrasound scan, taking less than 5 minutes to perform. If an AAA is detected, its size can be monitored over time by repeat scans. If it has grown to a large size (5.5 cm in diameter or more), surgery is usually recommended to prevent the AAA rupturing. Either open surgery or a key-hole technique (endovascular surgery) can be used to repair the aneurysm.


What about screening for AAA?

Because AAAs can be easily and reliably detected by ultrasound scanning which is quite cheap and very safe, research studies have been performed to find out if scanning large groups of people (screening) can prevent people dying from AAAs. Such ultrasound screening of men at age 65 for AAA has been shown to reduce deaths from AAA and to be cost-effective for the NHS.


What is this research project about?

It has previously been thought that because AAAs are much less common in women, it would not be worth the expense to the NHS of screening them for AAA. At present the national AAA screening programmes in the UK are restricted to men. In this project, we will work out whether screening women for AAA could save lives at a reasonable value for money to the NHS.


How will we work out if it is worthwhile to screen women for AAA?

The research team includes specialists in vascular surgery, AAA epidemiology, medical statistics and health economics, from the Universities of Cambridge, Leicester, Brunel and Imperial College. The team will identify published research studies and unpublished data that provide information about AAAs in women. Using a computer programme we will bring all of this information together and evaluate AAA screening in women. One main challenge will be to identify relevant and reliable information that applies to women alone. Another will be to investigate what possible changes there should be to the way AAA screening, surveillance and intervention are undertaken for women, as compared to the existing national screening programme in men – for example in terms of the age at screening and the AAA diameter threshold for consideration of surgery.


What will this project achieve?

The outputs from this research will have an immediate impact, either on national policy or on what additional studies are required. If it is clear that AAA screening in women is likely to both effective and cost-effective, this will be a major impetus to launch a national screening programme for women. The research will also provide information on how such a screening programme should be designed. If the conclusion about AAA screening in women is unclear, because some of the necessary information in women is either lacking or very uncertain, this research will point to what future studies are required in order to provide a more definitive answer.


When will we know the answer?

The project started in Spring 2015. Work will be completed by the end of 2016 and the official reports will be publicly available in 2017.


Who is paying for this?

This work is funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme, project number 14/179/01. More details of the project and the overall NIHR HTA Programme can be found if you click here: http://www.nets.nihr.ac.uk/projects/hta/1417901