Title: Female Aneurysm screening STudy - FAST
Funder: Department of Health and Social Care

Abstract: BACKGROUND: There is an urgent need to determine if the current policy of excluding women from abdominal aortic aneurysm (AAA) screening is justified or not. AAA rupture causes over 3,000 deaths per annum in England and Wales2. Even though AAA prevalence in women is lower than in men, the relative burden of disease in women is higher due to increased risks of both mortality and morbidity due to AAA rupture, and after surgery to prevent rupture, in females3-6. AAA rupture can be prevented by early detection and monitoring through screening and surveillance, and surgical repair if the AAA enlarges to a size when the risk of rupture outweighs the risk of surgery7-10. Since 2013 the NHS has been offering AAA screening to all men in the year of their 65th birthday. AAA screening in men has been shown to be cost-effective and reduce AAA-mortality11, 12. Women are not included in the NHS AAA Screening Programme, as there is currently no evidence that screening women is effective13. Women may be unfairly disadvantaged by this policy however. In 2013, 31.7% of all deaths due to ruptured AAA were in females2. Between 2000 and 2009, AAA-death rates fell by 5.6% per year in men but only 4.1% in women14. AAA in women are 4-times more likely to rupture than in men7. There is therefore a need to re-examine the screening of women for AAA. The NIHR has directly commissioned an HTA project (HTA 14/179/01) to develop a statistical model of AAA screening effectiveness in women but key missing inputs for this model are screening attendance rates and a contemporaneous estimate of AAA prevalence in women. If these could be provided it is likely that a national policy recommendation regarding AAA screening in women could be made, possibly without recourse to an expensive large-scale randomized clinical trial. AIMS: The primary aims of this study are to assess the feasibility of using routinely collected primary care data to identify women at high-risk of AAA by inviting these women for AAA screening, determine attendance rates, and assess the prevalence of AAA in these women. PLAN OF INVESTIGATION: We will use locally available primary care data to select a cohort of women at high risk of AAA to invite for AAA screening. We have analysed local general practice databases and have established that the risk factors of interest (coronary heart disease, current smoking and ex-smoking) are recorded on an individual patient basis and that there are adequate numbers of women with these risk factors in the proposed study area. We will invite women with these risk factors for AAA for screening and determine the uptake of AAA screening in those invited. We will screen 6612 women for AAA which will enable an accurate estimate of AAA prevalence such that we can be 99% confident that the true population prevalence in this high-risk group is above the prevalence threshold for screening cost-effectiveness of 0.35%. BENEFITS: Patient benefits Reduce the mortality and morbidity caused by AAA in women through the delivery of AAA screening, an intervention that is currently unavailable to women in the NHS. Establish female specific requirements for the provision of information before, during and after participation in screening. NHS benefits Reduce the number of admissions with ruptured AAAs in women (high cost episodes) and AAA related deaths in women. Maximise the cost-efficiency of future screening strategies for AAA by identifying a population at high risk. Establish a mechanism for the identification of women at high risk of AAA that is relevant to the NHS and can be instituted within current NHS informatics infrastructure.

Lay abstract: This research will open the way to protecting women who are most at risk of a fatal rupture of the main blood vessel from the heart &ndash; the aorta. Fatal rupture of the aorta is usually caused by a swelling of the aorta in the abdomen (an Abdominal Aortic Aneurysm, or AAA). If detected early, AAAs can be monitored and may be surgically repaired to prevent rupture. An AAA usually shows no symptoms but can usually be diagnosed easily and safely well before rupture by ultrasound scanning. Surgical repair is usually carried out when the size of the AAA is more than 5.5cm in diameter as below this size the risk of rupture is lower than the risk of surgery. Men are offered screening for AAA at age 65. Women are not screened because the disease is less common in females and screening of all women is not cost-effective. Deaths in men due to AAA have decreased over the last decade. In women, there has been a reduction in AAA death rates but to a lesser extent than in men and now women account for a third of all deaths caused by ruptured AAA. Recent research has highlighted the concentration of disease in certain high-risk groups of women such as smokers and those with heart disease. These risk factors are now routinely recorded by general practitioners. This research will determine whether it is feasible to use readily available general practice data to identify women at higher risk of AAA and offer them screening. We will determine how many women in these higher risk groups will attend if they are invited for AAA screening, and how many of them have AAAs. This will demonstrate whether targeting higher risk groups of women for AAA screening is feasible and can be clinically justified.

Research activity codes: 4.4 POPULATION SCREENING
Health categories: CARDIOVASCULAR