Supplementary Material for: Endovascular thrombectomy with or without bridging thrombolysis in acute ischemic stroke: A cost-effectiveness analysis

Background
There is unclear added benefit of intravenous thrombolysis (IVT) with endovascular thrombectomy (EVT). We performed a cost-effectiveness analysis to assess the cost-effectiveness comparing EVT with IVT versus EVT alone.

Methods
We used a decision tree to examine the short-term costs and outcomes at 90 days after the occurrence of index stroke to compare the cost-effectiveness of EVT alone with EVT plus IVT for patients with stroke. Subsequently, we developed a Markov state transition model to assess the costs and outcomes over 1-year, 5-year, and 20-year time horizons. We estimated total and incremental cost, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio.

Results
The average costs per patient were estimated to be $47,304, $49,510, $59,770 and $ 76,561 for EVT only strategy, and $55,482, $57,751, $68,314, and $85,611 for EVT with IVT over 90-day, 1-year, 5-year, and 20-year, respectively. The cost saving of EVT only strategy was driven by the avoided medication costs of IVT (ranging from $8,178 to $9,050). The additional IVT led to a slight decrease in QALY estimate during the 90-day time horizon (loss of 0.002 QALY), but a small gain over 1-year and 5-year time horizons (0.011, and 0.0636 QALY). At a willingness-to-pay threshold of $50,000 per QALY gained, the probabilities of EVT only to be cost-effective were 100%, 100%, and 99.3% over 90-day, 1-year, and 5-year time horizons.

Conclusion
Our cost-effectiveness model suggested that EVT only may be cost-effective for patients with acute ischemic stroke secondary to large vessel occlusion.