One-time screening for abdominal aortic aneurysm in Ontario, Canada: a model-based cost-utility analysis

Abstract

In Canada, about 20 000 people receive a diagnosis of an abdom inal aortic aneurysm (AAA) annually. 1 Males aged 65-80 years have an AAA prevalence 6 times higher than females of the same age. 2 Smoking, family history of AAA, coronary artery disease, athero sclerosis, hypercholesterolemia, and hypertension are other known risk factors. [3][4][5][6] Rupture of an AAA is often fatal, with prehospital and perioperative mortality rates of around 50%. 7 Scheduled AAA treat ments include open surgery or endovascular aneurysm repair, with mortality rates of 1%-5%. Timely detection of AAA is critical to allow prophylactic repair once the risk of rupture exceeds that of surgery. The Multicentre Aneurysm Screening Study randomized controlled trial (RCT) in the United Kingdom found a 42% reduction in AAArelated mortality over 13 years of followup after a onetime screening with ultrasonography among males aged 65-74 years. 8,9 In total, 4 RCTs have shown that onetime AAA screening reduces risk of AAArelated death, rupture, and emergency repair among males aged at least 65 years. 7 Among females, who were included in only 1 of 4 RCTs and accounted for 7% of the trial's sample, no significant benefit from screening was shown. 7 Although existing Canadian guidelines support AAA screening among males, they are inconsistent regarding screening among females. 1,7,10 The Canadian Task Force on Preventive Health Care recommends onetime screening with ultrasonography for AAA among males aged 65-80 years (weak recommendation, moderate quality of evi dence). 1 The Canadian Society for Vascular Surgery recommends onetime screening ultrasonography for all males aged 65-80 years (grade 1a [i.e., strong, highquality] evidence) and for all females aged 65-80 years with a history of smoking or cardiovascular dis ease (grade 2c [i.e., weak, lowquality] evidence). 7 Despite Canadian guidelines supportive of AAA screening, no provincial or territorial screening programs exist in Canada. In addition to uncertainty around the impact of AAA screening among females, one contributory knowledge gap may be a lack of contemporary evidence on the costeffectiveness of screening. In Canada, screening programs often receive public funding, in part based on economic evaluations considered by health technology