Research question:

Can the effectiveness of abdominal aortic aneurysm (AAA) screening be improved by targeting screening at individuals most likely to have an AAA, whilst ensuring that AAA detection rates remain acceptable to patients and the public?

Background:

Screening for AAA is both clinically and economically effective. The main determinant of this effectiveness is disease prevalence. AAA prevalence is decreasing over time, steadily reducing the efficiency of the current NHS AAA Screening Programme (NAAASP) screening policy. One alternative to whole population screening is targeted screening of high-risk groups such as smokers. Whether this would detect a clinically and publicly acceptable proportion of disease, and the extent to which it would improve cost-effectiveness is unknown. Aim: To determine the clinical outcomes and cost-effectiveness of targeted AAA screening.

Objectives:

1) Explore the ethical implications and public acceptability of targeted AAA screening;

2) Link individual mens’ NAAASP screening records to primary care records and prepare the linked dataset for analysis;

3) Use the linked dataset to undertake in-silico trials of targeted AAA screening including long-term clinical and economic effectiveness modelling.

Methods:

Rather than conduct an expensive and time consuming randomized trial to directly test targeted screening, we will undertake in-silico trials of targeted AAA screening. To determine success criteria for the in-silico trials, and as a specific research output, the ethics and issues around acceptability of targeted screening will first be explored using qualitative measures. To perform the in-silico trials individual mens’ outcomes from the NAAASP (2013 to 2021, 2,300,000 men, 1% with AAA) will be linked to primary care data from the Clinical Practice Research Datalink (CPRD) (20% overlap of records). Risk factors for AAA will be used as targeted screening criteria in in-silico trials, with diagnostic accuracy as the primary outcome. Trial results will be used to re-parameterise a discrete event simulation model of AAA screening to estimate the long-term (30 year) clinical and economic effectiveness of the targeted screening.

Timelines for delivery:

Months 0-9: PPI group training, literature review, focus groups, qualitative data analyses and data cleaning/preparation.

Months 10-18: PPI review of focus group work, targeted screening strategy development and in-silico trials.

Months 19-30: Long-term clinical and cost-effectiveness modelling, PPI review of results, dissemination.

Anticipated impact and dissemination:

We expect this project to have a direct and significant impact on NHS, UK and worldwide AAA screening policies. Our dissemination strategy will be to target those involved in screening policy decisions. The results of the research will be disseminated via our contact networks directly to Public Health England and the other UK AAA screening stakeholders, including an evidence review submission to the National Screening Committee. Conventional media will be used as the main route for public dissemination as this is the most effective way to reach those affected by this research. Academic audiences will be reached through peer-reviewed publications, conference presentations and online electronic dissemination.