Cost-effectiveness of endovascular treatment after 6–24 h in ischaemic stroke patients with collateral flow on CT-angiography: A model-based economic evaluation of the MR CLEAN-LATE trial

Background: The MR CLEAN-LATE trial has shown that patient selection for endovascular treatment (EVT) in the late window (6–24 h after onset or last-seen-well) based on the presence of collateral flow on CT-angiography is safe and effective. We aimed to assess the cost-effectiveness of late-window collateral-based EVT-selection compared to best medical management (BMM) over a lifetime horizon (until 95 years of age). Materials and Methods: A model-based economic evaluation was performed from a societal perspective in The Netherlands. A decision tree was combined with a state-transition (Markov) model. Health states were defined by the modified Rankin Scale (mRS). Initial probabilities at 3-months post-stroke were based on MR CLEAN-LATE data. Transition probabilities were derived from previous literature. Information on short- and long-term resource use and utilities was obtained from a study using MR CLEAN-LATE and cross-sectional data. All costs are expressed in 2022 euros. Costs and quality-adjusted life years (QALYs) were discounted at a rate of 4% and 1.5%, respectively. The effect of parameter uncertainty was assessed using probabilistic sensitivity analysis (PSA). Results: On average, the EVT strategy cost €159,592 (95% CI: €140,830–€180,154) and generated 3.46 QALYs (95% CI: 3.04–3.90) per patient, whereas the costs and QALYs associated with BMM were €149,935 (95% CI: €130,841–€171,776) and 2.88 (95% CI: 2.48–3.29), respectively. The incremental cost-effectiveness ratio per QALY and the incremental net monetary benefit were €16,442 and €19,710, respectively. At a cost-effectiveness threshold of €50,000/QALY, EVT was cost-effective in 87% of replications. Discussion and Conclusion: Collateral-based selection for late-window EVT is likely cost-effective from a societal perspective in The Netherlands. Graphical abstract