Abdominal aortic aneurysm (AAA or ‘triple A’) is a progressive condition, characterised by the abnormal weakening and widening of the abdominal section of the aorta, the largest blood vessel in the body. An AAA often develops slowly and without symptoms.

The prevalence of AAA is low until approximately 60 years of age and increases steadily thereafter. The most common risk factors for AAA include male sex, increasing age, family history of AAA, smoking, and cardiovascular risk factors, such as hypertension. There is no specific pharmacological treatment to slow or reverse AAA growth. Optimal management of AAA involves surveillance, management of cardiovascular risk factors, particularly smoking, and timely elective surgical repair, where indicated.

An AAA can be detected using a simple, non-invasive ultrasound scan, which measures the diameter of the abdominal aorta. In the absence of AAA screening, people without symptoms are typically detected incidentally during imaging for other indications. AAA may be detected if patients present with symptoms such as pain or a palpable mass, or as a medical emergency following rupture. A ruptured AAA is a life-threatening event, with a mortality rate of up to 80%, even with emergency surgery.

There is currently no population-based screening programme for AAA in Ireland. Given that AAA typically has no symptoms and the severe consequences of AAA rupture, early detection through screening could reduce AAA-related morbidity and mortality. 

This HTA was carried out in accordance with HIQA’s guidelines for the conduct of HTAs. In summary, the following took place:

• The Terms of Reference and deliverables for the HTA were agreed between HIQA and the Chair of NSAC, on behalf of NSAC.
• An Expert Advisory Group (EAG) was convened by HIQA comprising representation from relevant stakeholders. These included patient representation from the Irish Heart Foundation, public representation from the Irish Senior Citizens Parliament, the Department of Health, the National Screening Service (NSS), the Faculty of Radiologists and Radiation Oncologists, the National Clinical Programme for Surgery, the National Clinical Programme for Critical Care, Primary Care, and international expertise from the National Health Service (NHS) AAA Screening Programme. An Evaluation Team was appointed comprising HIQA staff.
• The epidemiology and burden of AAA in Ireland and internationally was described.
  The current care pathway for patients with AAA in Ireland, and the proposed care pathway for screening, were described.
• A review of international policy and guidelines on screening for AAA was conducted.
• A systematic review of the clinical effectiveness and safety of screening for AAA in men was conducted.
• A systematic review of the cost effectiveness of screening for AAA in men was conducted.
• The organisational and budgetary implications of introducing a screening programme for AAA in men in the Irish context were described and estimated.
• A description was provided of the ethical, patient and societal considerations that the introduction of a screening programme for AAA for men may have for patients, families, the general public and the healthcare system in Ireland.
• A draft report outlining the findings of this HTA was discussed at a meeting of the EAG and subsequently amended, where appropriate.
• The draft report was circulated to the EAG for review, and was subsequently published for public and targeted consultation.
  Informed by the consultation feedback, a revised draft report was prepared and circulated to the EAG for review.
• Following review by the EAG, the final draft of the HTA was submitted to the Board of HIQA for approval.
• Following approval from the Board of HIQA, the final HTA was submitted to NSAC for consideration and published on the HIQA website. 
   

• An abdominal aortic aneurysm is a swelling or bulge in the abdominal section of the aorta. In men, the prevalence increases from approximately age 65. Recent evidence from international screening programmes suggests that the current prevalence in men aged 65 is less than 1%, with decreasing prevalence observed in recent years.

• Despite the evidence of declining prevalence, AAA remains an important public health issue. A ruptured AAA is a life-threatening event, with a mortality rate of up to 80%. It is estimated that between 2007 and 2021, on average, up to 115 men died from AAA in Ireland each year.

• The typically asymptomatic nature of AAA, the high mortality rate following rupture, the availability of a simple, accurate test with good acceptability, and the availability of an effective treatment, suggest that AAA is a suitable candidate for screening.

• It is likely that the benefit-harm balance, at present, still favours screening. However, the clinical effectiveness and cost effectiveness of population-based screening appears to be diminishing over time in the context of declining AAA prevalence, improved cardiovascular risk factor management, and the increasing use of imaging as part of usual care. 

  • As a result of declining AAA prevalence, there may be a shift towards population-based AAA screening no longer being cost effective over the next five to 10 years. There is therefore increasing international interest in targeted screening. However, the evidence base for organised targeted screening is not yet developed.

  • In the context of a finite healthcare budget, the longevity of the programme should be considered as part of any investment decision. If a screening programme is likely to be discontinued due to evidence of limited benefits, the significant time and financial resources required to establish the programme may not be proportionate to the additional health benefits gained.

• Given the core requirements of a screening programme as set out in the NSAC criteria including the need for appropriate care pathways, staffing, and facilities, and the importance of robust data in informing decision-making, a considerable development phase would be necessary. Consideration should be given to the collection of AAA prevalence and vascular service data, and enhancement of radiology and vascular service capacity.