Long-term outcomes of the western australian trial of screening for abdominal aortic aneurysms: Secondary analysis of a randomized clinical trial

Abstract

Importance: Mortality from ruptured abdominal aortic aneurysms (AAAs) remains high. The benefit of screening older men for AAAs needs to be assessed in a range of health care settings. Objective: To assess the influence of screening for AAAs in men aged 64 to 83 years on mortality from AAAs. Design, Setting, and Participants: This randomized clinical trial performed from April 1, 1996, through March 31, 1999, with a mean of 12.8 years of follow-up (range, 11.6-14.2 years) included a population-based sample from a single metropolitan region in Western Australia identified via the electoral roll. Data analysis was performed from June 1, 2015, to June 1, 2016. Interventions: Randomization to an invitation to undergo ultrasonography of the abdominal aorta or a control group without invitation. Main Outcomes and Measures: Surgery for and mortality from AAA. Results: A total of 49 801 men aged 64 to 83 years were identified for the study. Men living too far from screening centers (n = 8671) or who died before invitation (n = 2650) were excluded, resulting in 19 249 men in the invited group and 19 231 controls (mean [SD] age, 72.5 [4.6] years; 95% white). Of 19 249 men invited for screening, 12 203 (63.4%) attended. There were more elective operations (536 vs 414, P < .001) and fewer ruptured AAAs (72 vs 99, P = .04) in the invited group compared with the control group. Overall, there were 90 deaths from AAAs in the invited group (mortality rate, 47.86 per 100 000 person-years; 95% CI, 38.93-58.84) and 98 in the control group (52.53 per 100 000 person-years; 95% CI, 43.09-64.03) for a rate ratio of 0.91 (95% CI, 0.68-1.21). For men aged 65 to 74 years, the AAA mortality rate in the invited group was 34.52 per 100 000 person-years (95% CI, 26.02-45.81) compared with 37.67 per 100 000 person-years (95% CI, 28.71-49.44) in the control group for a rate ratio of 0.92 (95% CI, 0.62-1.36). The number needed to invite for screening to prevent 1 death from an AAA in 5 years was 4784 for men aged 64 to 83 years and 3290 for men aged 65 to 74 years. There were no meaningful differences in all-cause, cardiovascular, and other mortality risks. Conclusions and Relevance: Use of the electoral roll to identify and invite men aged 64 to 83 years for screening for AAAs had no significant effect on the overall mortality from AAAs.