Screening for Abdominal Aortic Aneurysm

University dissertation from Uppsala : Acta Universitatis Upsaliensis

Abstract: Randomised controlled trials have demonstrated that mortality from Abdominal Aortic Aneurysm (AAA) can be cost-effectively reduced by ultrasound-screening of men. Evidence for screening women is insufficient. Reports of falling AAA incidence are emerging.In an effort to study screening for AAA in a contemporary setting, two cross-sectional multi-centre population-based studies of one-time screening of 65-year-old men, and 70-year-old women in Middle Sweden were undertaken. Cost-efficiency of one-time screening of 65-year-old men was evaluated in a decision-analysis model. Five-year outcomes in men invited to screening at age 65 and age 70, were studied in a longitudinal cohort study.A lower than expected (1.7%) prevalence of AAA in 65-year-old men was found, as well as a very low (0.4%) prevalence in 70-year-old women. Smoking was the dominating risk factor associated with AAA, but the association was stronger in women. The main cause of reduced contemporary prevalence was falling smoking rates in the population since 30 years.One-time screening of 65-year-old men was found to be cost-effective and deliver significant clinical impact. The cost per quality adjusted life-year gained, at 13-years follow-up, was €14706, which was below the recommended UK NICE threshold of €25000. 15 lives were saved by inviting 10000 to screening. Prevalence of AAA and the rate of incidental detection of AAAs in the population were important factors affecting cost-efficiency.New AAAs developed after 5 years in men screened normal at age 65, predominantly in men with sub-aneurysmal aortas (25-29mm) at 65, and smokers. The 5-year rate of AAA repair was high among men with screening detected AAAs, as was non-AAA related mortality. Ruptures were only documented among non-attenders.Conclusions: A lower than expected prevalence of AAA among 65-year-old men, an unchanged repair rate, and improved longevity of the elderly population was found. Although one-time screening for AAA was still cost-effective within a contemporary context, several issues need to be addressed; the threshold diameter for follow-up, the current rate of opportunistic detection of AAA in the population, re-screening of the entire population at a higher age, and targeted screening of smokers. Screening 70-year-old women who do not smoke is likely to be futile, thus ruling out population screening of women for AAA.

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