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Abdominal aortic aneurysms (AAAs) are present in about 5 to 10% of men aged 65 to 79 years.1 Generally, they expand without causing symptoms until they rupture, or, the individual dies of an unrelated cause. AAA rupture is a surgical emergency, and less than half of rupture patients reach the hospital alive. Emergency repair itself carries a high operative mortality of 30 to 65%,2-4 attributable to haemodynamic compromise, advanced age, and medical comorbidities. Overall, AAA rupture carries a mortality rate as high as 80 to 90%.3,5-8 In contrast, elective repair is associated with a considerably lower operative mortality, between 3 and 10%.9-14
Population-based AAA screening programmes use abdominal ultrasound scans to detect AAAs before they rupture. Four major randomised controlled trials evaluating AAA population screening have been performed to date.9 15-17 Meta-analysis of these shows that AAA screening reduces AAA-related mortality by about 40% in males aged 65 to 79 years.18 However, issues of concern include the risk of overtreatment, the benefit-harm balance of elective repair, and health system capacity. (see companion article in this NZMJ issue for further discussion on AAA screening).
The United Kingdom began gradually implementing population screening for AAA in 2009, screening males aged 65 years.19 In the United States, Medicare has covered AAA screening in male ever-smokers aged 65 to 75 and females with a family history of AAA since 2007.20 There is currently no policy for AAA screening in New Zealand, although "awareness of the research evidence for screening is high."21
The evidence base for AAA screening draws heavily from international studies. The relatively small body of local research has been focused mainly on in-hospital mortality from rupture, selection criteria for emergency repair, clinical presentation of rupture, risk factors, and endovascular repair analysis. There is a lack of recent national-level information on overall epidemiology of AAA events and deaths, both in and out of hospital. This information is essential to inform any policy around AAA screening in New Zealand.
Accordingly, the objective of this study is to describe the burden of AAA disease in New Zealand by AAA events, AAA-related deaths, and vascular surgical workload. It also aims to describe AAA events and deaths by age, sex, ethnicity, and operative status. This is the first of two papers; the...