Patient-Centred Abdominal Aortic Aneurysm Study (PCAAAS)

A study to improve the quality of care for men who have regular screening to check on the growth of an abdominal aortic aneurysm (AAA).



An abdominal aortic aneurysm (AAA) is a swelling in the aorta, a vessel that runs from the heart down through the chest and stomach.

AAAs can increase in size over time and burst. Most people who have a burst AAA will die before they get to a hospital or do not survive emergency surgery. 4,000 people die each year in England and Wales from a burst AAA.

Screening can pick up an AAA before it bursts. It saves lives and is cost-effective. The National AAA Screening Programme (NAAASP) offers screenings to all men aged 65. It invites 300,000 patients for scans each year, and there are now 15,000 patients in surveillance: that is, having scans regularly. Those found to have a small AAA are checked each year to see how much it has grown. Those who have a medium AAA are checked every three months. When patients are found to have a large AAA, they are offered surgery to stop it from bursting.

There are two challenges to ensuring that the benefits of screening outweigh the harms. First, patients (and their partners) can suffer "psychosocial consequences" of screening: anxiety, distress, the burden of protecting others from worrying, guilt, helplessness, and uncertainty. We need to find ways to reduce these problems.

Second, as patients get older they may become unfit for surgery and cannot have treatment. Understanding men’s preferences for leaving the surveillance programme would inform the development of a patient-centred exit strategy so that patients, their partners, and clinicians can make informed decisions about actively leaving surveillance.

Design and methods

There are two work packages.

First, we will develop a new intervention to reduce the psychological consequences of screening. We will do a survey of screening providers (n=4 types of staff in 38 centres) to find out what they think might help patients to reduce anxiety. We will do a survey of patients ‘in surveillance’ to measure who has problems and when this is worse (n=1200). We will identify patients with problems and interview them (n=20-24) and their partners (n=12-20) about what might help them manage anxiety.

Service providers and patients will then co-design an intervention. We will create this intervention and assess if patients use it and like it.

In the second work package, we will identify patients' preferences for leaving the surveillance programme. We will interview patients (n=20-24) in surveillance and their partners (n=12-20) about their preferences for exiting surveillance under different circumstances. Then we will undertake a survey of patients in surveillance (n=500) to measure their preferences and the intensity of their preferences. We will feed this into the NAAASP to help them develop a patient-centred exit strategy.

Patient and public involvement (PPI)

Our PPI co-applicant is a PPI member of the NAAASP Research Committee. We have talked to four men who have been in the screening programme or had treatment for AAA to help us develop this project.

We will form the first AAA PPI group to work with our study and future studies. The group will meet 10 times and be involved in the co-design of the intervention.

Two PPI members will sit on the Project Oversight Group.


The findings will be fed directly to the NHS England & Improvement AAA Screening Programme

Operational Delivery Group and the NHS England & Improvement Screening Programme Board.