Optimising surveillance intervals and re-intervention strategy following elective endovascular repair of abdominal aortic aneurysms

Background Elective endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm has an initial survival advantage over open repair (OR), but more frequent complications increase costs and long-term aneurysm-related mortality. Randomised controlled trials of EVAR versus OR have shown EVAR is not cost-effective over a patient’s lifetime. However, in the EVAR-1 trial, post-operative surveillance may have been sub-optimal, as the importance of sac growth as a predictor of graft failure was overlooked. Methods Real-world data informed a discrete event simulation model of post-operative outcomes following EVAR. Outcomes observed EVAR-1 were compared with those from five alternative post-operative surveillance and re-intervention strategies. Key events, quality-adjusted life years and costs were predicted. The impact of using complication and rupture rates from more recent devices, imaging and re-intervention methods was also explored. Results Compared with observed EVAR-1 outcomes, modelling full adherence to the EVAR-1 scan protocol reduced AAA deaths by 3% and increased elective re-interventions by 44%. European Society re17 intervention guidelines provided the most clinically effective strategy, with an 8% reduction in AAA deaths, but a 52% increase in elective re-interventions. The cheapest and most cost-effective strategy used lifetime annual ultrasound in primary care with confirmatory CT if necessary, and reduced AAA20 related deaths by 5%. Using contemporary rates for complications and rupture did not alter these conclusions. Conclusions All alternative strategies improved clinical benefits compared with the EVAR-1 trial. Further work is needed regarding the cost and accuracy of primary care ultrasound, and the potential impact of these strategies in the comparison with OR.

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