Mechanical Thrombectomy in Patients With Acute Ischemic Stroke: A Health Technology Assessment

In Ontario, current treatment for eligible patients who have an acute ischemic stroke is intravenous thrombolysis (IVT). However, there are some limitations and contraindications to IVT, and outcomes may not be favourable for patients with stroke caused by a proximal intracranial occlusion. An alternative is mechanical thrombectomy with newer devices, and a number of recent studies have suggested that this treatment is more effective for improving functional independence and clinical outcomes. The objective of this health technology assessment was to evaluate the clinical effectiveness and cost-effectiveness of new-generation mechanical thrombectomy devices (with or without IVT) compared to IVT alone (if eligible) in patients with acute ischemic stroke.

We conducted a systematic review of the literature, limited to randomized controlled trials that examined the effectiveness of mechanical thrombectomy using stent retrievers and thromboaspiration devices for patients with acute ischemic stroke. We assessed the quality of the evidence using the GRADE approach. We developed a Markov decision-analytic model to assess the cost-effectiveness of mechanical thrombectomy (with or without IVT) versus IVT alone (if eligible), calculated incremental cost-effectiveness ratios using a 5-year time horizon, and conducted sensitivity analyses to examine the robustness of the estimates.

There was a substantial, statistically significant difference in rate of functional independence (GRADE: high quality) between those who received mechanical thrombectomy (with or without IVT) and IVT alone (odds ratio [OR] 2.39, 95% confidence interval [CI] 1.88-3.04). We did not observe a difference in mortality (GRADE: moderate quality) (OR 0.80, 95% CI 0.60-1.07) or symptomatic intracerebral hemorrhage (GRADE: moderate quality) (OR 1.11, 95% CI 0.66-1.87). In the base-case cost-utility analysis, which had a 5 year time horizon, the costs and effectiveness for mechanical thrombectomy were $126,939 and 1.484 quality-adjusted life-years (QALYs) (2.969 life-years). The costs and effectiveness for IVT alone were $124,419 and 1.273 QALYs (2.861 life-years), respectively. Mechanical thrombectomy was associated with an incremental cost-effectiveness ratio of $11,990 per QALY gained. Probabilistic sensitivity analysis showed that the probability of mechanical thrombectomy being cost-effective was 57.5%, 89.7%, and 99.6%, at thresholds of $20,000, $50,000, and $100,000 per QALY gained, respectively. We estimated that adopting mechanical thrombectomy would lead to a cost increase of approximately $1 to 2 million.

High quality evidence showed that mechanical thrombectomy significantly improved functional independence and appeared to be cost-effective compared to IVT alone for patients with acute ischemic stroke.