Optimal Follow-up Strategies After Aorto-iliac Prosthetic Reconstruction: A Decision Analysis and Cost-effectiveness Analysis

Abstract

Objective. The primary aim of ultrasound follow-up after aorto-iliac prosthetic reconstruction is to correct false aneurysms before rupture occurs. We investigated whether follow-up improves the life expectancy of patients and sought to identify the most cost-effective follow-up strategy. Design of the Study. A Monte Carlo Markov decision model was constructed. The occurrence of false aneurysms was modelled as a time-dependent process for each anastomotic site, based on published series. Using this model, the impact of various follow-up strategies was investigated for three types of prostheses, aorto-distal tube, aorto-bi-iliac, and aorto-bi-femoral prostheses. Main outcome measures were discounted quality adjusted life years (dQALYs), discounted costs, and (discounted) cost-effectiveness (CE) ratios. Results. Follow-up of patients with aorto-distal tube and aorto-bifemoral prostheses did not result in an improvement life expectancy and was not cost-effective, QALYs 7.53 and 7.62 years, respectively. The results for aorto-distal tube and aorto-bifemoral prostheses were not sensitive to any variation in the model parameters. In the base case analysis, the life expectancy of patients with aorto-bi-iliac prostheses was 7.50 QALYs (95% confidence interval 7.46–7.54) whether or not they underwent routine follow-up. However, patients aged 54 years or younger gained 0.11 QALYs with annual follow-up ( p<0.05). The most cost-effective strategy was annual follow-up that starts 10 years after the initial operation, and continues up to 30 years after surgery (4600 Euro; CE ratio 21,000 Euro per QALY). When perioperative mortality of elective reconstruction of false aneurysms is 2% or lower (e.g. when endovascular treatment is used), a small improvement is observed (7.56 vs. 7.50 QALYs; p<0.05; CE ratio 35,000 Euro per QALY). Conclusions. Annual follow-up of aorto-bi-iliac prostheses should be restricted to patients aged 54 or younger and not start before 10 years after surgery. The same strategy can only be considered for older patients if mortality for secondary intervention is lower than 2%. Since patients with aorto-distal tube and aorto-bi-femoral prostheses do not benefit from follow-up for the detection of false aneurysms, this practice should be discouraged in these patient groups.